Sharing Channel Occupancy Ratio Information

ABSTRACT

A first base station central unit (BS-CU) communicates, with one or more wireless devices, packets via a first cell operating in an unlicensed spectrum. The BS-CU receives, from a first base station distributed unit (BS-DU), a channel occupancy ratio (CR) of the first cell, wherein the CR is for a plurality of time intervals and indicates utilization of unlicensed channel resources that have been utilized for transmissions by the first cell. The BS-CU transmits, to a second base station, the CR.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No. 16/925,405, filed Jul. 10, 2020, which claims the benefit of U.S. Provisional Application No. 62/872,471, filed Jul. 10, 2019, all of which are hereby incorporated by reference in their entireties.

BRIEF DESCRIPTION OF THE DRAWINGS

Examples of several of the various embodiments of the present disclosure are described herein with reference to the drawings.

FIG. 1A illustrates an example of a mobile communication network as per an aspect of an example embodiment of the present disclosure.

FIG. 1B illustrates another example mobile communication network as per an aspect of an example embodiment of the present disclosure.

FIG. 2A illustrates a New Radio (NR) user plane protocol stack comprising five layers implemented in a User Equipment (UE) and a Generation Node B (gNB) as per an aspect of an example embodiment of the present disclosure.

FIG. 2B illustrates a NR control plane protocol stack comprising six layers implemented in one or more of a UE, a gNB, and an Access and Mobility Management Function (AMF) as per an aspect of an example embodiment of the present disclosure.

FIG. 3 illustrates an example of services provided between protocol layers of the NR user plane protocol stack of FIG. 2A as per an aspect of an example embodiment of the present disclosure.

FIG. 4A illustrates an example downlink data flow through the NR user plane protocol stack of FIG. 2A as per an aspect of an example embodiment of the present disclosure.

FIG. 4B illustrates an example format of a MAC subheader in a MAC PDU as per an aspect of an example embodiment of the present disclosure.

FIG. 5A illustrates a mapping between logical channels, transport channels, and physical channels for downlink as per an aspect of an example embodiment of the present disclosure.

FIG. 5B illustrates a mapping between logical channels, transport channels, and physical channels for uplink as per an aspect of an example embodiment of the present disclosure.

FIG. 6 is an example diagram showing RRC state transitions of a UE as per an aspect of an example embodiment of the present disclosure.

FIG. 7 illustrates an example configuration of an NR frame into which OFDM symbols are grouped as per an aspect of an example embodiment of the present disclosure.

FIG. 8 illustrates an example configuration of a slot in the time and frequency domain for an NR carrier as per an aspect of an example embodiment of the present disclosure.

FIG. 9 illustrates an example of bandwidth adaptation using three configured BWPs for an NR carrier as per an aspect of an example embodiment of the present disclosure.

FIG. 10A illustrates the three carrier aggregation configurations with two component carriers as per an aspect of an example embodiment of the present disclosure.

FIG. 10B illustrates an example of how aggregated cells may be configured into one or more PUCCH groups as per an aspect of an example embodiment of the present disclosure.

FIG. 11A illustrates an example diagram of a protocol structure of a UE with carrier aggregation (CA) and/or dual connectivity (DC) as per an aspect of an example embodiment of the present disclosure.

FIG. 11B illustrates an example diagram of a protocol structure of multiple base stations with CA and/or DC as per an aspect of an example embodiment of the present disclosure.

FIG. 12 illustrates an example of a transmitter and a receiver having multiple antennas as per an aspect of an example embodiment of the present disclosure.

FIG. 13 illustrates an example of CSI-RSs that are mapped in the time and frequency domain as per an aspect of an example embodiment of the present disclosure s.

FIG. 14A illustrates examples of three downlink beam management procedures as per an aspect of an example embodiment of the present disclosure.

FIG. 14B illustrates examples of three uplink beam management procedures as per an aspect of an example embodiment of the present disclosure.

FIG. 15 illustrates an example of a beam failure recovery procedure as per an aspect of an example embodiment of the present disclosure.

FIG. 16 illustrates an example of an SS/PBCH block's structure and location as per an aspect of an example embodiment of the present disclosure.

FIG. 17A illustrates a four-step contention-based random access procedure as per an aspect of an example embodiment of the present disclosure.

FIG. 17B illustrates a two-step contention-free random access procedure as per an aspect of an example embodiment of the present disclosure.

FIG. 17C illustrates another two-step random access procedure as per an aspect of an example embodiment of the present disclosure.

FIG. 18A illustrates an example of CORESET configurations for a bandwidth part as per an aspect of an example embodiment of the present disclosure.

FIG. 18B illustrates an example of a CCE-to-REG mapping for DCI transmission on a CORESET and PDCCH processing as per an aspect of an example embodiment of the present disclosure.

FIG. 19 illustrates an example of a wireless device in communication with a base station as per an aspect of an example embodiment of the present disclosure.

FIG. 20A illustrates an example structure for uplink transmission as per an aspect of an example embodiment of the present disclosure.

FIG. 20B illustrates an example structure for modulation and up-conversion of a baseband signal to a carrier frequency as per an aspect of an example embodiment of the present disclosure.

FIG. 20C illustrates an example structure for downlink transmissions as per an aspect of an example embodiment of the present disclosure.

FIG. 20D illustrates another example structure for modulation and up-conversion of a baseband signal to a carrier frequency as per an aspect of an example embodiment of the present disclosure.

FIG. 21A, FIG. 22B, FIG. 22C and FIG. 22D illustrate deployment scenarios of D2D communications as per aspects of an example embodiments of the present disclosure.

FIG. 22A and FIG. 22B illustrate a resource pool for D2D communication as per an aspect of an example embodiment of the present disclosure.

FIG. 23 is an example of inband emission model as per an aspect of an example embodiment of the present disclosure.

FIG. 24 is an example diagram for V2X scenario as per an aspect of an example embodiment of the present disclosure.

FIG. 25 is an example of cyclic delay diversity as per an aspect of an example embodiment of the present disclosure.

FIG. 26 is a diagram of an aspect of an example embodiment of the present disclosure.

FIG. 27 is a diagram of an aspect of an example embodiment of the present disclosure.

FIG. 28 is a diagram of an aspect of an example embodiment of the present disclosure.

FIG. 29 is a diagram of an aspect of an example embodiment of the present disclosure.

FIG. 30 is a diagram of an aspect of an example embodiment of the present disclosure.

FIG. 31 is a diagram of an aspect of an example embodiment of the present disclosure.

FIG. 32 is a diagram of an aspect of an example embodiment of the present disclosure.

FIG. 33 is a diagram of an aspect of an example embodiment of the present disclosure.

FIG. 34 is a diagram of an aspect of an example embodiment of the present disclosure.

FIG. 35 is a diagram of an aspect of an example embodiment of the present disclosure.

FIG. 36 is a diagram of an aspect of an example embodiment of the present disclosure.

FIG. 37 is a diagram of an aspect of an example embodiment of the present disclosure.

FIG. 38 is a diagram of an aspect of an example embodiment of the present disclosure.

FIG. 39 is a diagram of an aspect of an example embodiment of the present disclosure.

FIG. 40 is a diagram of an aspect of an example embodiment of the present disclosure.

DETAILED DESCRIPTION

In the present disclosure, various embodiments are presented as examples of how the disclosed techniques may be implemented and/or how the disclosed techniques may be practiced in environments and scenarios. It will be apparent to persons skilled in the relevant art that various changes in form and detail can be made therein without departing from the scope. In fact, after reading the description, it will be apparent to one skilled in the relevant art how to implement alternative embodiments. The present embodiments should not be limited by any of the described exemplary embodiments. The embodiments of the present disclosure will be described with reference to the accompanying drawings. Limitations, features, and/or elements from the disclosed example embodiments may be combined to create further embodiments within the scope of the disclosure. Any figures which highlight the functionality and advantages, are presented for example purposes only. The disclosed architecture is sufficiently flexible and configurable, such that it may be utilized in ways other than that shown. For example, the actions listed in any flowchart may be re-ordered or only optionally used in some embodiments.

Embodiments may be configured to operate as needed. The disclosed mechanism may be performed when certain criteria are met, for example, in a wireless device, a base station, a radio environment, a network, a combination of the above, and/or the like. Example criteria may be based, at least in part, on for example, wireless device or network node configurations, traffic load, initial system set up, packet sizes, traffic characteristics, a combination of the above, and/or the like. When the one or more criteria are met, various example embodiments may be applied. Therefore, it may be possible to implement example embodiments that selectively implement disclosed protocols.

A base station may communicate with a mix of wireless devices. Wireless devices and/or base stations may support multiple technologies, and/or multiple releases of the same technology. Wireless devices may have some specific capability(ies) depending on wireless device category and/or capability(ies). When this disclosure refers to a base station communicating with a plurality of wireless devices, this disclosure may refer to a subset of the total wireless devices in a coverage area. This disclosure may refer to, for example, a plurality of wireless devices of a given LTE or 5G release with a given capability and in a given sector of the base station. The plurality of wireless devices in this disclosure may refer to a selected plurality of wireless devices, and/or a subset of total wireless devices in a coverage area which perform according to disclosed methods, and/or the like. There may be a plurality of base stations or a plurality of wireless devices in a coverage area that may not comply with the disclosed methods, for example, those wireless devices or base stations may perform based on older releases of LTE or 5G technology.

In this disclosure, “a” and “an” and similar phrases are to be interpreted as “at least one” and “one or more.” Similarly, any term that ends with the suffix “(s)” is to be interpreted as “at least one” and “one or more.” In this disclosure, the term “may” is to be interpreted as “may, for example.” In other words, the term “may” is indicative that the phrase following the term “may” is an example of one of a multitude of suitable possibilities that may, or may not, be employed by one or more of the various embodiments. The terms “comprises” and “consists of”, as used herein, enumerate one or more components of the element being described. The term “comprises” is interchangeable with “includes” and does not exclude unenumerated components from being included in the element being described. By contrast, “consists of” provides a complete enumeration of the one or more components of the element being described. The term “based on”, as used herein, should be interpreted as “based at least in part on” rather than, for example, “based solely on”. The term “and/or” as used herein represents any possible combination of enumerated elements. For example, “A, B, and/or C” may represent A; B; C; A and B; A and C; B and C; or A, B, and C.

If A and B are sets and every element of A is an element of B, A is called a subset of B. In this specification, only non-empty sets and subsets are considered. For example, possible subsets of B={cell1, cell2} are: {cell1}, {cell2}, and {cell1, cell2}. The phrase “based on” (or equally “based at least on”) is indicative that the phrase following the term “based on” is an example of one of a multitude of suitable possibilities that may, or may not, be employed to one or more of the various embodiments. The phrase “in response to” (or equally “in response at least to”) is indicative that the phrase following the phrase “in response to” is an example of one of a multitude of suitable possibilities that may, or may not, be employed to one or more of the various embodiments. The phrase “depending on” (or equally “depending at least to”) is indicative that the phrase following the phrase “depending on” is an example of one of a multitude of suitable possibilities that may, or may not, be employed to one or more of the various embodiments. The phrase “employing/using” (or equally “employing/using at least”) is indicative that the phrase following the phrase “employing/using” is an example of one of a multitude of suitable possibilities that may, or may not, be employed to one or more of the various embodiments.

The term configured may relate to the capacity of a device whether the device is in an operational or non-operational state. Configured may refer to specific settings in a device that effect the operational characteristics of the device whether the device is in an operational or non-operational state. In other words, the hardware, software, firmware, registers, memory values, and/or the like may be “configured” within a device, whether the device is in an operational or nonoperational state, to provide the device with specific characteristics. Terms such as “a control message to cause in a device” may mean that a control message has parameters that may be used to configure specific characteristics or may be used to implement certain actions in the device, whether the device is in an operational or non-operational state.

In this disclosure, parameters (or equally called, fields, or Information elements: IEs) may comprise one or more information objects, and an information object may comprise one or more other objects. For example, if parameter (IE) N comprises parameter (IE) M, and parameter (IE) M comprises parameter (IE) K, and parameter (IE) K comprises parameter (information element) J. Then, for example, N comprises K, and N comprises J. In an example embodiment, when one or more messages comprise a plurality of parameters, it implies that a parameter in the plurality of parameters is in at least one of the one or more messages, but does not have to be in each of the one or more messages.

Many features presented are described as being optional through the use of “may” or the use of parentheses. For the sake of brevity and legibility, the present disclosure does not explicitly recite each and every permutation that may be obtained by choosing from the set of optional features. The present disclosure is to be interpreted as explicitly disclosing all such permutations. For example, a system described as having three optional features may be embodied in seven ways, namely with just one of the three possible features, with any two of the three possible features or with three of the three possible features.

Many of the elements described in the disclosed embodiments may be implemented as modules. A module is defined here as an element that performs a defined function and has a defined interface to other elements. The modules described in this disclosure may be implemented in hardware, software in combination with hardware, firmware, wetware (e.g. hardware with a biological element) or a combination thereof, which may be behaviorally equivalent. For example, modules may be implemented as a software routine written in a computer language configured to be executed by a hardware machine (such as C, C++, FORTRAN, JAVA, BASIC, MATLAB or the like) or a modeling/simulation program such as SIMULINK, STATEFLOW, GNU OCTAVE, or LAB VIEW MATHSCRIPT. It may be possible to implement modules using physical hardware that incorporates discrete or programmable analog, digital and/or quantum hardware. Examples of programmable hardware comprise: computers, microcontrollers, microprocessors, application-specific integrated circuits (ASICs); field programmable gate arrays (FPGAs); and complex programmable logic devices (CPLDs). Computers, microcontrollers and microprocessors are programmed using languages such as assembly, C, C++ or the like. FPGAs, ASICs and CPLDs are often programmed using hardware description languages (HDL) such as VHSIC hardware description language (VHDL) or Verilog that configure connections between internal hardware modules with lesser functionality on a programmable device. The mentioned technologies are often used in combination to achieve the result of a functional module.

The following acronyms are used throughout the present disclosure:

3G Third Generation

3GPP Third-Generation Partnership Project

4G Fourth Generation

5G Fifth Generation

5G-CN Fifth Generation Core Network

5GS Fifth Generation System

AF Application Function

AM Acknowledged Mode

AMF Access and Mobility Management Function

ARQ Automatic Repeat Request

AS Access Stratum

ASIC Application Specific Integrated Circuit

AUSF Authentication Server Function

BCCH Broadcast Control Channel

BCH Broadcast Channel

BFR Beam Failure Recovery

BS Base Station

BWP Bandwidth Part

CA Carrier Aggregation

CC Component Carriers

CCCH Common Control Channel

CCE Control Channel Element

CDM Code Division Multiplexing

CD-SSB Cell-Defining SSB

Cell ID Cell Identifier

CE Control Element

CN Core Network

CORESET Control Resource Set

CQI Channel Quality Indicator

CRC Cyclic Redundancy Check

CRI CSI-RS Resource Index

C-RNTI Cell RNTI

CS-RNTI Configured Scheduling RNTI

CSI Channel State Information

CSI-RS Channel State Information Reference Signal

CU Central Unit

DC Dual Connectivity

DCCH Dedicated Control Channel

DCI Downlink Control Information

DFT Discrete Fourier Transform

DL SCC Downlink Secondary CC

DL-SCH Downlink Shared Channel

DMRS Demodulation Reference Signal

DN Data Network

DRX Discontinuous Reception

DSP Digital Signal Processor

DTCH Dedicated Traffic Channel

DU Distributed Unit

eNB Evolved Node B

EN-DC E-UTRA-NR Dual Connectivity

EPC Evolved Packet Core

E-UTRA Evolved UMTS Terrestrial Radio Access

FDD Frequency Division Duplexing

FDM Frequency Division Multiplexing

FM Frequency Modulated

FPGA Field Programmable Gate Array

GC-PDCCH Group Common PDCCH

gNB-CU Generation Node B Central Unit

gNB-DU Generation Node B Distributed Unit

gNB Generation Node B

HARQ Hybrid Automatic Repeat Request

HARQ-ACK HARQ Acknowledgement

IFFT Inverse Fast Fourier Transform

IMSI International Mobile Subscriber Identity

INT-RNTI Interruption RNTI

IoT Internet of Things

IP Internet Protocol

LCID Logical Channel Identifier

LTE Long-Term Evolution

MAC Media Access Control

MCG Master Cell Group

MCS Modulation and Coding Scheme

MIB Master Information Block

MIMO Multiple-Input Multiple-Output

MN Master Node

M-PSK M-phase Shift Keying

M-QAM M-quadrature Amplitude Modulation

MR-DC Multi-radio Dual Connectivity

NAS Non-Access Stratum

NCGI NR Cell Global Identifier

NE-DC NR-E-UTRA dual connectivity

NEF Network Exposure Function

NG-C NG-Control Plane

ng-eNB Next Generation Evolved Node B

NGEN-DC NG-RAN E-UTRA-NR dual connectivity

NG-RAN Next-Generation Radio Access Network

NG-U NG-User Plane

NR New Radio

NR-DC NR-NR dual connectivity

NRF NR Repository Function

NUL Normal Uplink

OAM Operations, Administration, and Maintenance

OFDM Orthogonal Frequency Divisional Multiplexing

OSI Open Systems Interconnection

PAPR Peak to Average Power Ratio

PBCH Physical Broadcast Channel

PCCH Paging Control Channel

PCell Primary Cell

PCF Policy Control Function

PCH Paging Channel

PCI Physical Cell Identifier

PDCCH Physical Downlink Control Channel

PDCP Packet Data Convergence Protocol

PDSCH Physical Downlink Shared Channel

PDU Protocol (or Packet) Data Unit

PHY Physical

PLMN Public Land Mobile Network

PMI Precoding Matrix Indicator

PRACH Physical Random Access Channel

PRB Physical Resource Block

PRG Precoding Resource Block Group

P-RNTI Paging RNTI

PSCell Primary Secondary Cell

PSS Primary Synchronization Signal

PT-RS Phase-Tracking Reference Signal

PUSCH Physical Uplink Shared Channel

QCL Quasi Co-located

QFI QoS Flow Indicator

QPSK Quadrature Phase Shift Keying

QoS Quality of Service

RACH Random Access Channel

RAI RAN Area Identifier

RAN Radio Access Network

RAR Random Access Response

RA-RNTI Random Access RNTI

RAT Radio Access Technology

RB Resource Block

RE Resource Element

REG Resource-element Group

RF Radio Frequency

RI Rand Indicator

RLC Radio Link Control

RLF Radio Link Failure

RMSI Remaining Minimum System Information

RNTI Radio Network Temporary Identifier

RRC Radio Resource Control

RRH Remote Radio Heads

RSRP Reference Signal Receive Power

RSRQ Reference Signal Received Quality

RS Reference Signal

RSU Road Side Unit

Rx Receive

SC-FDMA Single Carrier-Frequency Division Multiple Access

SCG Secondary Cell Group

SDAP Service Data Application Protocol

SDU Service Data Unit

SFI Slot Formation Indication

SFN System Frame Number

SI System Information

SIB System Information Block

SIB1 System Information Block Type 1

SINR Signal to Interference Plus Noise Ratio

SI-RNTI System Information RNTI

SMF Session Management Function

SN Secondary Node

SP-CSI-RNTI Semi-Persistent CSI RNTI

SR Scheduling Requests

SRS Sounding Reference Signal

SSS Secondary Synchronization Signals

SUL Supplementary Uplink

TAI Tracking Area Identifier

TB Transport Block

TCI Transmission Configuration Indication

TC-RNTI Temporary Cell RNTI

TDD Time-Division Duplexing

TDM Time Domain Multiplexing

TM Transparent Mode

TPC Transmission Power Control

TRP Transmission Reception Point

TTI Transmission Time Interval

Tx Transmit

UCI Uplink Control Information

UDM Unified Data Management

UE User Equipment

UL SCC Uplink Secondary CC

UL-SCH Uplink Shared Channel

UM Unacknowledged Mode

UMTS Universal Mobile Telecommunications System

UPF User Plane Function

USB Universal Serial Bus

UT User Terminal

UTRA UMTS Terrestrial Radio Access

FIG. 1A illustrates an example of a mobile communication network 100 in which embodiments of the present disclosure may be implemented. The mobile communication network 100 may be, for example, a public land mobile network (PLMN) run by a network operator. As illustrated in FIG. 1A, the mobile communication network 100 includes a core network (CN) 102, a radio access network (RAN) 104, and a wireless device 106.

The CN 102 may provide the wireless device 106 with an interface to one or more data networks (DNs), such as public DNs (e.g., the Internet), private DNs, and/or intra-operator DNs. As part of the interface functionality, the CN 102 may set up end-to-end connections between the wireless device 106 and the one or more DNs, authenticate the wireless device 106, and provide charging functionality.

The RAN 104 may connect the CN 102 to the wireless device 106 through radio communications over an air interface. As part of the radio communications, the RAN 104 may provide scheduling, radio resource management, and retransmission protocols. The communication direction from the RAN 104 to the wireless device 106 over the air interface is known as the downlink and the communication direction from the wireless device 106 to the RAN 104 over the air interface is known as the uplink. Downlink transmissions may be separated from uplink transmissions using frequency division duplexing (FDD), time-division duplexing (TDD), and/or some combination of the two duplexing techniques.

The term wireless device may be used throughout this disclosure to refer to and encompass any mobile device or fixed (non-mobile) device for which wireless communication is needed or usable. For example, a wireless device may be a telephone, smart phone, tablet, computer, laptop, sensor, meter, wearable device, Internet of Things (IoT) device, vehicle road side unit (RSU), relay node, automobile, and/or any combination thereof. The term wireless device encompasses other terminology, including user equipment (UE), user terminal (UT), access terminal (AT), mobile station, handset, wireless transmit and receive unit (WTRU), and/or wireless communication device.

The RAN 104 may include one or more base stations (not shown). The term base station may be used throughout this disclosure to refer to and encompass a Node B (associated with UMTS and/or 3G standards), an Evolved Node B (eNB, associated with E-UTRA and/or 4G standards), a remote radio head (RRH), a baseband processing unit coupled to one or more RRHs, a repeater node or relay node used to extend the coverage area of a donor node, a Next Generation Evolved Node B (ng-eNB), a Generation Node B (gNB, associated with NR and/or 5G standards), an access point (AP, associated with, for example, Wi-Fi or any other suitable wireless communication standard), and/or any combination thereof. A base station may comprise at least one gNB Central Unit (gNB-CU) and at least one a gNB Distributed Unit (gNB-DU).

A base station included in the RAN 104 may include one or more sets of antennas for communicating with the wireless device 106 over the air interface. For example, one or more of the base stations may include three sets of antennas to respectively control three cells (or sectors). The size of a cell may be determined by a range at which a receiver (e.g., a base station receiver) can successfully receive the transmissions from a transmitter (e.g., a wireless device transmitter) operating in the cell. Together, the cells of the base stations may provide radio coverage to the wireless device 106 over a wide geographic area to support wireless device mobility.

In addition to three-sector sites, other implementations of base stations are possible. For example, one or more of the base stations in the RAN 104 may be implemented as a sectored site with more or less than three sectors. One or more of the base stations in the RAN 104 may be implemented as an access point, as a baseband processing unit coupled to several remote radio heads (RRHs), and/or as a repeater or relay node used to extend the coverage area of a donor node. A baseband processing unit coupled to RRHs may be part of a centralized or cloud RAN architecture, where the baseband processing unit may be either centralized in a pool of baseband processing units or virtualized. A repeater node may amplify and rebroadcast a radio signal received from a donor node. A relay node may perform the same/similar functions as a repeater node but may decode the radio signal received from the donor node to remove noise before amplifying and rebroadcasting the radio signal.

The RAN 104 may be deployed as a homogenous network of macrocell base stations that have similar antenna patterns and similar high-level transmit powers. The RAN 104 may be deployed as a heterogeneous network. In heterogeneous networks, small cell base stations may be used to provide small coverage areas, for example, coverage areas that overlap with the comparatively larger coverage areas provided by macrocell base stations. The small coverage areas may be provided in areas with high data traffic (or so-called “hotspots”) or in areas with weak macrocell coverage. Examples of small cell base stations include, in order of decreasing coverage area, microcell base stations, picocell base stations, and femtocell base stations or home base stations.

The Third-Generation Partnership Project (3GPP) was formed in 1998 to provide global standardization of specifications for mobile communication networks similar to the mobile communication network 100 in FIG. 1A. To date, 3GPP has produced specifications for three generations of mobile networks: a third generation (3G) network known as Universal Mobile Telecommunications System (UMTS), a fourth generation (4G) network known as Long-Term Evolution (LTE), and a fifth generation (5G) network known as 5G System (5GS). Embodiments of the present disclosure are described with reference to the RAN of a 3GPP 5G network, referred to as next-generation RAN (NG-RAN). Embodiments may be applicable to RANs of other mobile communication networks, such as the RAN 104 in FIG. 1A, the RANs of earlier 3G and 4G networks, and those of future networks yet to be specified (e.g., a 3GPP 6G network). NG-RAN implements 5G radio access technology known as New Radio (NR) and may be provisioned to implement 4G radio access technology or other radio access technologies, including non-3GPP radio access technologies.

FIG. 1B illustrates another example mobile communication network 150 in which embodiments of the present disclosure may be implemented. Mobile communication network 150 may be, for example, a PLMN run by a network operator. As illustrated in FIG. 1B, mobile communication network 150 includes a 5G core network (5G-CN) 152, an NG-RAN 154, and UEs 156A and 156B (collectively UEs 156). These components may be implemented and operate in the same or similar manner as corresponding components described with respect to FIG. 1A.

The 5G-CN 152 provides the UEs 156 with an interface to one or more DNs, such as public DNs (e.g., the Internet), private DNs, and/or intra-operator DNs. As part of the interface functionality, the 5G-CN 152 may set up end-to-end connections between the UEs 156 and the one or more DNs, authenticate the UEs 156, and provide charging functionality. Compared to the CN of a 3GPP 4G network, the basis of the 5G-CN 152 may be a service-based architecture. This means that the architecture of the nodes making up the 5G-CN 152 may be defined as network functions that offer services via interfaces to other network functions. The network functions of the 5G-CN 152 may be implemented in several ways, including as network elements on dedicated or shared hardware, as software instances running on dedicated or shared hardware, or as virtualized functions instantiated on a platform (e.g., a cloud-based platform).

As illustrated in FIG. 1B, the 5G-CN 152 includes an Access and Mobility Management Function (AMF) 158A and a User Plane Function (UPF) 158B, which are shown as one component AMF/UPF 158 in FIG. 1B for ease of illustration. The UPF 158B may serve as a gateway between the NG-RAN 154 and the one or more DNs. The UPF 158B may perform functions such as packet routing and forwarding, packet inspection and user plane policy rule enforcement, traffic usage reporting, uplink classification to support routing of traffic flows to the one or more DNs, quality of service (QoS) handling for the user plane (e.g., packet filtering, gating, uplink/downlink rate enforcement, and uplink traffic verification), downlink packet buffering, and downlink data notification triggering. The UPF 158B may serve as an anchor point for intra-/inter-Radio Access Technology (RAT) mobility, an external protocol (or packet) data unit (PDU) session point of interconnect to the one or more DNs, and/or a branching point to support a multi-homed PDU session. The UEs 156 may be configured to receive services through a PDU session, which is a logical connection between a UE and a DN.

The AMF 158A may perform functions such as Non-Access Stratum (NAS) signaling termination, NAS signaling security, Access Stratum (AS) security control, inter-CN node signaling for mobility between 3GPP access networks, idle mode UE reachability (e.g., control and execution of paging retransmission), registration area management, intra-system and inter-system mobility support, access authentication, access authorization including checking of roaming rights, mobility management control (subscription and policies), network slicing support, and/or session management function (SMF) selection. NAS may refer to the functionality operating between a CN and a UE, and AS may refer to the functionality operating between the UE and a RAN.

The 5G-CN 152 may include one or more additional network functions that are not shown in FIG. 1B for the sake of clarity. For example, the 5G-CN 152 may include one or more of a Session Management Function (SMF), an NR Repository Function (NRF), a Policy Control Function (PCF), a Network Exposure Function (NEF), a Unified Data Management (UDM), an Application Function (AF), and/or an Authentication Server Function (AUSF).

The NG-RAN 154 may connect the 5G-CN 152 to the UEs 156 through radio communications over the air interface. The NG-RAN 154 may include one or more gNBs, illustrated as gNB 160A and gNB 160B (collectively gNBs 160) and/or one or more ng-eNBs, illustrated as ng-eNB 162A and ng-eNB 162B (collectively ng-eNBs 162). The gNBs 160 and ng-eNBs 162 may be more generically referred to as base stations. The gNBs 160 and ng-eNBs 162 may include one or more sets of antennas for communicating with the UEs 156 over an air interface. For example, one or more of the gNBs 160 and/or one or more of the ng-eNBs 162 may include three sets of antennas to respectively control three cells (or sectors). Together, the cells of the gNBs 160 and the ng-eNBs 162 may provide radio coverage to the UEs 156 over a wide geographic area to support UE mobility.

As shown in FIG. 1B, the gNBs 160 and/or the ng-eNBs 162 may be connected to the 5G-CN 152 by means of an NG interface and to other base stations by an Xn interface. The NG and Xn interfaces may be established using direct physical connections and/or indirect connections over an underlying transport network, such as an internet protocol (IP) transport network. The gNBs 160 and/or the ng-eNBs 162 may be connected to the UEs 156 by means of a Uu interface. For example, as illustrated in FIG. 1B, gNB 160A may be connected to the UE 156A by means of a Uu interface. The NG, Xn, and Uu interfaces are associated with a protocol stack. The protocol stacks associated with the interfaces may be used by the network elements in FIG. 1B to exchange data and signaling messages and may include two planes: a user plane and a control plane. The user plane may handle data of interest to a user. The control plane may handle signaling messages of interest to the network elements.

The gNBs 160 and/or the ng-eNBs 162 may be connected to one or more AMF/UPF functions of the 5G-CN 152, such as the AMF/UPF 158, by means of one or more NG interfaces. For example, the gNB 160A may be connected to the UPF 158B of the AMF/UPF 158 by means of an NG-User plane (NG-U) interface. The NG-U interface may provide delivery (e.g., non-guaranteed delivery) of user plane PDUs between the gNB 160A and the UPF 158B. The gNB 160A may be connected to the AMF 158A by means of an NG-Control plane (NG-C) interface. The NG-C interface may provide, for example, NG interface management, UE context management, UE mobility management, transport of NAS messages, paging, PDU session management, and configuration transfer and/or warning message transmission.

The gNBs 160 may provide NR user plane and control plane protocol terminations towards the UEs 156 over the Uu interface. For example, the gNB 160A may provide NR user plane and control plane protocol terminations toward the UE 156A over a Uu interface associated with a first protocol stack. The ng-eNBs 162 may provide Evolved UMTS Terrestrial Radio Access (E-UTRA) user plane and control plane protocol terminations towards the UEs 156 over a Uu interface, where E-UTRA refers to the 3GPP 4G radio-access technology. For example, the ng-eNB 162B may provide E-UTRA user plane and control plane protocol terminations towards the UE 156B over a Uu interface associated with a second protocol stack.

The 5G-CN 152 was described as being configured to handle NR and 4G radio accesses. It will be appreciated by one of ordinary skill in the art that it may be possible for NR to connect to a 4G core network in a mode known as “non-standalone operation.” In non-standalone operation, a 4G core network is used to provide (or at least support) control-plane functionality (e.g., initial access, mobility, and paging). Although only one AMF/UPF 158 is shown in FIG. 1B, one gNB or ng-eNB may be connected to multiple AMF/UPF nodes to provide redundancy and/or to load share across the multiple AMF/UPF nodes.

As discussed, an interface (e.g., Uu, Xn, and NG interfaces) between the network elements in FIG. 1B may be associated with a protocol stack that the network elements use to exchange data and signaling messages. A protocol stack may include two planes: a user plane and a control plane. The user plane may handle data of interest to a user, and the control plane may handle signaling messages of interest to the network elements.

FIG. 2A and FIG. 2B respectively illustrate examples of NR user plane and NR control plane protocol stacks for the Uu interface that lies between a UE 210 and a gNB 220. The protocol stacks illustrated in FIG. 2A and FIG. 2B may be the same or similar to those used for the Uu interface between, for example, the UE 156A and the gNB 160A shown in FIG. 1B.

FIG. 2A illustrates a NR user plane protocol stack comprising five layers implemented in the UE 210 and the gNB 220. At the bottom of the protocol stack, physical layers (PHYs) 211 and 221 may provide transport services to the higher layers of the protocol stack and may correspond to layer 1 of the Open Systems Interconnection (OSI) model. The next four protocols above PHYs 211 and 221 comprise media access control layers (MACs) 212 and 222, radio link control layers (RLCs) 213 and 223, packet data convergence protocol layers (PDCPs) 214 and 224, and service data application protocol layers (SDAPs) 215 and 225. Together, these four protocols may make up layer 2, or the data link layer, of the OSI model.

FIG. 3 illustrates an example of services provided between protocol layers of the NR user plane protocol stack. Starting from the top of FIG. 2A and FIG. 3 , the SDAPs 215 and 225 may perform QoS flow handling. The UE 210 may receive services through a PDU session, which may be a logical connection between the UE 210 and a DN. The PDU session may have one or more QoS flows. A UPF of a CN (e.g., the UPF 158B) may map IP packets to the one or more QoS flows of the PDU session based on QoS requirements (e.g., in terms of delay, data rate, and/or error rate). The SDAPs 215 and 225 may perform mapping/de-mapping between the one or more QoS flows and one or more data radio bearers. The mapping/de-mapping between the QoS flows and the data radio bearers may be determined by the SDAP 225 at the gNB 220. The SDAP 215 at the UE 210 may be informed of the mapping between the QoS flows and the data radio bearers through reflective mapping or control signaling received from the gNB 220. For reflective mapping, the SDAP 225 at the gNB 220 may mark the downlink packets with a QoS flow indicator (QFI), which may be observed by the SDAP 215 at the UE 210 to determine the mapping/de-mapping between the QoS flows and the data radio bearers.

The PDCPs 214 and 224 may perform header compression/decompression to reduce the amount of data that needs to be transmitted over the air interface, ciphering/deciphering to prevent unauthorized decoding of data transmitted over the air interface, and integrity protection (to ensure control messages originate from intended sources. The PDCPs 214 and 224 may perform retransmissions of undelivered packets, in-sequence delivery and reordering of packets, and removal of packets received in duplicate due to, for example, an intra-gNB handover. The PDCPs 214 and 224 may perform packet duplication to improve the likelihood of the packet being received and, at the receiver, remove any duplicate packets. Packet duplication may be useful for services that require high reliability.

Although not shown in FIG. 3 , PDCPs 214 and 224 may perform mapping/de-mapping between a split radio bearer and RLC channels in a dual connectivity scenario. Dual connectivity is a technique that allows a UE to connect to two cells or, more generally, two cell groups: a master cell group (MCG) and a secondary cell group (SCG). A split bearer is when a single radio bearer, such as one of the radio bearers provided by the PDCPs 214 and 224 as a service to the SDAPs 215 and 225, is handled by cell groups in dual connectivity. The PDCPs 214 and 224 may map/de-map the split radio bearer between RLC channels belonging to cell groups.

The RLCs 213 and 223 may perform segmentation, retransmission through Automatic Repeat Request (ARQ), and removal of duplicate data units received from MACs 212 and 222, respectively. The RLCs 213 and 223 may support three transmission modes: transparent mode (TM); unacknowledged mode (UM); and acknowledged mode (AM). Based on the transmission mode an RLC is operating, the RLC may perform one or more of the noted functions. The RLC configuration may be per logical channel with no dependency on numerologies and/or Transmission Time Interval (TTI) durations. As shown in FIG. 3 , the RLCs 213 and 223 may provide RLC channels as a service to PDCPs 214 and 224, respectively.

The MACs 212 and 222 may perform multiplexing/demultiplexing of logical channels and/or mapping between logical channels and transport channels. The multiplexing/demultiplexing may include multiplexing/demultiplexing of data units, belonging to the one or more logical channels, into/from Transport Blocks (TBs) delivered to/from the PHYs 211 and 221. The MAC 222 may be configured to perform scheduling, scheduling information reporting, and priority handling between UEs by means of dynamic scheduling. Scheduling may be performed in the gNB 220 (at the MAC 222) for downlink and uplink. The MACs 212 and 222 may be configured to perform error correction through Hybrid Automatic Repeat Request (HARQ) (e.g., one HARQ entity per carrier in case of Carrier Aggregation (CA)), priority handling between logical channels of the UE 210 by means of logical channel prioritization, and/or padding. The MACs 212 and 222 may support one or more numerologies and/or transmission timings. In an example, mapping restrictions in a logical channel prioritization may control which numerology and/or transmission timing a logical channel may use. As shown in FIG. 3 , the MACs 212 and 222 may provide logical channels as a service to the RLCs 213 and 223.

The PHYs 211 and 221 may perform mapping of transport channels to physical channels and digital and analog signal processing functions for sending and receiving information over the air interface. These digital and analog signal processing functions may include, for example, coding/decoding and modulation/demodulation. The PHYs 211 and 221 may perform multi-antenna mapping. As shown in FIG. 3 , the PHYs 211 and 221 may provide one or more transport channels as a service to the MACs 212 and 222.

FIG. 4A illustrates an example downlink data flow through the NR user plane protocol stack. FIG. 4A illustrates a downlink data flow of three IP packets (n, n+1, and m) through the NR user plane protocol stack to generate two TBs at the gNB 220. An uplink data flow through the NR user plane protocol stack may be similar to the downlink data flow depicted in FIG. 4A.

The downlink data flow of FIG. 4A begins when SDAP 225 receives the three IP packets from one or more QoS flows and maps the three packets to radio bearers. In FIG. 4A, the SDAP 225 maps IP packets n and n+1 to a first radio bearer 402 and maps IP packet m to a second radio bearer 404. An SDAP header (labeled with an “H” in FIG. 4A) is added to an IP packet. The data unit from/to a higher protocol layer is referred to as a service data unit (SDU) of the lower protocol layer and the data unit to/from a lower protocol layer is referred to as a protocol data unit (PDU) of the higher protocol layer. As shown in FIG. 4A, the data unit from the SDAP 225 is an SDU of lower protocol layer PDCP 224 and is a PDU of the SDAP 225.

The remaining protocol layers in FIG. 4A may perform their associated functionality (e.g., with respect to FIG. 3 ), add corresponding headers, and forward their respective outputs to the next lower layer. For example, the PDCP 224 may perform IP-header compression and ciphering and forward its output to the RLC 223. The RLC 223 may optionally perform segmentation (e.g., as shown for IP packet m in FIG. 4A) and forward its output to the MAC 222. The MAC 222 may multiplex a number of RLC PDUs and may attach a MAC subheader to an RLC PDU to form a transport block. In NR, the MAC subheaders may be distributed across the MAC PDU, as illustrated in FIG. 4A. In LTE, the MAC subheaders may be entirely located at the beginning of the MAC PDU. The NR MAC PDU structure may reduce processing time and associated latency because the MAC PDU subheaders may be computed before the full MAC PDU is assembled.

FIG. 4B illustrates an example format of a MAC subheader in a MAC PDU. The MAC subheader includes: an SDU length field for indicating the length (e.g., in bytes) of the MAC SDU to which the MAC subheader corresponds; a logical channel identifier (LCID) field for identifying the logical channel from which the MAC SDU originated to aid in the demultiplexing process; a flag (F) for indicating the size of the SDU length field; and a reserved bit (R) field for future use.

FIG. 4B further illustrates MAC control elements (CEs) inserted into the MAC PDU by a MAC, such as MAC 223 or MAC 222. For example, FIG. 4B illustrates two MAC CEs inserted into the MAC PDU. MAC CEs may be inserted at the beginning of a MAC PDU for downlink transmissions (as shown in FIG. 4B) and at the end of a MAC PDU for uplink transmissions. MAC CEs may be used for in-band control signaling. Example MAC CEs include: scheduling-related MAC CEs, such as buffer status reports and power headroom reports; activation/deactivation MAC CEs, such as those for activation/deactivation of PDCP duplication detection, channel state information (CSI) reporting, sounding reference signal (SRS) transmission, and prior configured components; discontinuous reception (DRX) related MAC CEs; timing advance MAC CEs; and random access related MAC CEs. A MAC CE may be preceded by a MAC subheader with a similar format as described for MAC SDUs and may be identified with a reserved value in the LCID field that indicates the type of control information included in the MAC CE.

Before describing the NR control plane protocol stack, logical channels, transport channels, and physical channels are first described as well as a mapping between the channel types. One or more of the channels may be used to carry out functions associated with the NR control plane protocol stack described later below.

FIG. 5A and FIG. 5B illustrate, for downlink and uplink respectively, a mapping between logical channels, transport channels, and physical channels. Information is passed through channels between the RLC, the MAC, and the PHY of the NR protocol stack. A logical channel may be used between the RLC and the MAC and may be classified as a control channel that carries control and configuration information in the NR control plane or as a traffic channel that carries data in the NR user plane. A logical channel may be classified as a dedicated logical channel that is dedicated to a specific UE or as a common logical channel that may be used by more than one UE. A logical channel may also be defined by the type of information it carries. The set of logical channels defined by NR include, for example:

-   -   a paging control channel (PCCH) for carrying paging messages         used to page a UE whose location is not known to the network on         a cell level;     -   a broadcast control channel (BCCH) for carrying system         information messages in the form of a master information block         (MIB) and several system information blocks (SIBs), wherein the         system information messages may be used by the UEs to obtain         information about how a cell is configured and how to operate         within the cell;     -   a common control channel (CCCH) for carrying control messages         together with random access;     -   a dedicated control channel (DCCH) for carrying control messages         to/from a specific the UE to configure the UE; and     -   a dedicated traffic channel (DTCH) for carrying user data         to/from a specific the UE.

Transport channels are used between the MAC and PHY layers and may be defined by how the information they carry is transmitted over the air interface. The set of transport channels defined by NR include, for example:

-   -   a paging channel (PCH) for carrying paging messages that         originated from the PCCH;     -   a broadcast channel (BCH) for carrying the MIB from the BCCH;     -   a downlink shared channel (DL-SCH) for carrying downlink data         and signaling messages, including the SIBs from the BCCH;     -   an uplink shared channel (UL-SCH) for carrying uplink data and         signaling messages; and     -   a random access channel (RACH) for allowing a UE to contact the         network without any prior scheduling.

The PHY may use physical channels to pass information between processing levels of the PHY. A physical channel may have an associated set of time-frequency resources for carrying the information of one or more transport channels. The PHY may generate control information to support the low-level operation of the PHY and provide the control information to the lower levels of the PHY via physical control channels, known as L1/L2 control channels. The set of physical channels and physical control channels defined by NR include, for example:

-   -   a physical broadcast channel (PBCH) for carrying the MIB from         the BCH;     -   a physical downlink shared channel (PDSCH) for carrying downlink         data and signaling messages from the DL-SCH, as well as paging         messages from the PCH;     -   a physical downlink control channel (PDCCH) for carrying         downlink control information (DCI), which may include downlink         scheduling commands, uplink scheduling grants, and uplink power         control commands;     -   a physical uplink shared channel (PUSCH) for carrying uplink         data and signaling messages from the UL-SCH and in some         instances uplink control information (UCI) as described below;     -   a physical uplink control channel (PUCCH) for carrying UCI,         which may include HARQ acknowledgments, channel quality         indicators (CQI), pre-coding matrix indicators (PMI), rank         indicators (RI), and scheduling requests (SR); and     -   a physical random access channel (PRACH) for random access.

Similar to the physical control channels, the physical layer generates physical signals to support the low-level operation of the physical layer. As shown in FIG. 5A and FIG. 5B, the physical layer signals defined by NR include: primary synchronization signals (PSS), secondary synchronization signals (SSS), channel state information reference signals (CSI-RS), demodulation reference signals (DMRS), sounding reference signals (SRS), and phase-tracking reference signals (PT-RS). These physical layer signals will be described in greater detail below.

FIG. 2B illustrates an example NR control plane protocol stack. As shown in FIG. 2B, the NR control plane protocol stack may use the same/similar first four protocol layers as the example NR user plane protocol stack. These four protocol layers include the PHYs 211 and 221, the MACs 212 and 222, the RLCs 213 and 223, and the PDCPs 214 and 224. Instead of having the SDAPs 215 and 225 at the top of the stack as in the NR user plane protocol stack, the NR control plane stack has radio resource controls (RRCs) 216 and 226 and NAS protocols 217 and 237 at the top of the NR control plane protocol stack.

The NAS protocols 217 and 237 may provide control plane functionality between the UE 210 and the AMF 230 (e.g., the AMF 158A) or, more generally, between the UE 210 and the CN. The NAS protocols 217 and 237 may provide control plane functionality between the UE 210 and the AMF 230 via signaling messages, referred to as NAS messages. There is no direct path between the UE 210 and the AMF 230 through which the NAS messages can be transported. The NAS messages may be transported using the AS of the Uu and NG interfaces. NAS protocols 217 and 237 may provide control plane functionality such as authentication, security, connection setup, mobility management, and session management.

The RRCs 216 and 226 may provide control plane functionality between the UE 210 and the gNB 220 or, more generally, between the UE 210 and the RAN. The RRCs 216 and 226 may provide control plane functionality between the UE 210 and the gNB 220 via signaling messages, referred to as RRC messages. RRC messages may be transmitted between the UE 210 and the RAN using signaling radio bearers and the same/similar PDCP, RLC, MAC, and PHY protocol layers. The MAC may multiplex control-plane and user-plane data into the same transport block (TB). The RRCs 216 and 226 may provide control plane functionality such as: broadcast of system information related to AS and NAS; paging initiated by the CN or the RAN; establishment, maintenance and release of an RRC connection between the UE 210 and the RAN; security functions including key management; establishment, configuration, maintenance and release of signaling radio bearers and data radio bearers; mobility functions; QoS management functions; the UE measurement reporting and control of the reporting; detection of and recovery from radio link failure (RLF); and/or NAS message transfer. As part of establishing an RRC connection, RRCs 216 and 226 may establish an RRC context, which may involve configuring parameters for communication between the UE 210 and the RAN.

FIG. 6 is an example diagram showing RRC state transitions of a UE. The UE may be that same or similar to the wireless device 106 depicted in FIG. 1A, the UE 210 depicted in FIG. 2A and FIG. 2B, or any other wireless device described in the present disclosure. As illustrated in FIG. 6 , a UE may be in at least one of three RRC states: RRC connected 602 (e.g., RRC_CONNECTED), RRC idle 604 (e.g., RRC_IDLE), and RRC inactive 606 (e.g., RRC_INACTIVE).

In RRC connected 602, the UE has an established RRC context and may have at least one RRC connection with a base station. The base station may be similar to one of the one or more base stations included in the RAN 104 depicted in FIG. 1A, one of the gNBs 160 or ng-eNBs 162 depicted in FIG. 1B, the gNB 220 depicted in FIG. 2A and FIG. 2B, or any other base station described in the present disclosure. The base station with which the UE is connected may have the RRC context for the UE. The RRC context, referred to as the UE context, may comprise parameters for communication between the UE and the base station. These parameters may include, for example: one or more AS contexts; one or more radio link configuration parameters; bearer configuration information (e.g., relating to a data radio bearer, signaling radio bearer, logical channel, QoS flow, and/or PDU session); security information; and/or PHY, MAC, RLC, PDCP, and/or SDAP layer configuration information. While in RRC connected 602, mobility of the UE may be managed by the RAN (e.g., the RAN 104 or the NG-RAN 154). The UE may measure the signal levels (e.g., reference signal levels) from a serving cell and neighboring cells and report these measurements to the base station currently serving the UE. The UE's serving base station may request a handover to a cell of one of the neighboring base stations based on the reported measurements. The RRC state may transition from RRC connected 602 to RRC idle 604 through a connection release procedure 608 or to RRC inactive 606 through a connection inactivation procedure 610.

In RRC idle 604, an RRC context may not be established for the UE. In RRC idle 604, the UE may not have an RRC connection with the base station. While in RRC idle 604, the UE may be in a sleep state for the majority of the time (e.g., to conserve battery power). The UE may wake up periodically (e.g., once in every discontinuous reception cycle) to monitor for paging messages from the RAN. Mobility of the UE may be managed by the UE through a procedure known as cell reselection. The RRC state may transition from RRC idle 604 to RRC connected 602 through a connection establishment procedure 612, which may involve a random access procedure as discussed in greater detail below.

In RRC inactive 606, the RRC context previously established is maintained in the UE and the base station. This allows for a fast transition to RRC connected 602 with reduced signaling overhead as compared to the transition from RRC idle 604 to RRC connected 602. While in RRC inactive 606, the UE may be in a sleep state and mobility of the UE may be managed by the UE through cell reselection. The RRC state may transition from RRC inactive 606 to RRC connected 602 through a connection resume procedure 614 or to RRC idle 604 though a connection release procedure 616 that may be the same as or similar to connection release procedure 608.

An RRC state may be associated with a mobility management mechanism. In RRC idle 604 and RRC inactive 606, mobility is managed by the UE through cell reselection. The purpose of mobility management in RRC idle 604 and RRC inactive 606 is to allow the network to be able to notify the UE of an event via a paging message without having to broadcast the paging message over the entire mobile communications network. The mobility management mechanism used in RRC idle 604 and RRC inactive 606 may allow the network to track the UE on a cell-group level so that the paging message may be broadcast over the cells of the cell group that the UE currently resides within instead of the entire mobile communication network. The mobility management mechanisms for RRC idle 604 and RRC inactive 606 track the UE on a cell-group level. They may do so using different granularities of grouping. For example, there may be three levels of cell-grouping granularity: individual cells; cells within a RAN area identified by a RAN area identifier (RAI); and cells within a group of RAN areas, referred to as a tracking area and identified by a tracking area identifier (TAI).

Tracking areas may be used to track the UE at the CN level. The CN (e.g., the CN 102 or the 5G-CN 152) may provide the UE with a list of TAIs associated with a UE registration area. If the UE moves, through cell reselection, to a cell associated with a TAI not included in the list of TAIs associated with the UE registration area, the UE may perform a registration update with the CN to allow the CN to update the UE's location and provide the UE with a new the UE registration area.

RAN areas may be used to track the UE at the RAN level. For a UE in RRC inactive 606 state, the UE may be assigned a RAN notification area. A RAN notification area may comprise one or more cell identities, a list of RAIs, or a list of TAIs. In an example, a base station may belong to one or more RAN notification areas. In an example, a cell may belong to one or more RAN notification areas. If the UE moves, through cell reselection, to a cell not included in the RAN notification area assigned to the UE, the UE may perform a notification area update with the RAN to update the UE's RAN notification area.

A base station storing an RRC context for a UE or a last serving base station of the UE may be referred to as an anchor base station. An anchor base station may maintain an RRC context for the UE at least during a period of time that the UE stays in a RAN notification area of the anchor base station and/or during a period of time that the UE stays in RRC inactive 606.

A gNB, such as gNBs 160 in FIG. 1B, may be split in two parts: a central unit (gNB-CU), and one or more distributed units (gNB-DU). A gNB-CU may be coupled to one or more gNB-DUs using an F1 interface. The gNB-CU may comprise the RRC, the PDCP, and the SDAP. A gNB-DU may comprise the RLC, the MAC, and the PHY.

In NR, the physical signals and physical channels (discussed with respect to FIG. 5A and FIG. 5B) may be mapped onto orthogonal frequency divisional multiplexing (OFDM) symbols. OFDM is a multicarrier communication scheme that transmits data over F orthogonal subcarriers (or tones). Before transmission, the data may be mapped to a series of complex symbols (e.g., M-quadrature amplitude modulation (M-QAM) or M-phase shift keying (M-PSK) symbols), referred to as source symbols, and divided into F parallel symbol streams. The F parallel symbol streams may be treated as though they are in the frequency domain and used as inputs to an Inverse Fast Fourier Transform (IFFT) block that transforms them into the time domain. The IFFT block may take in F source symbols at a time, one from each of the F parallel symbol streams, and use each source symbol to modulate the amplitude and phase of one of F sinusoidal basis functions that correspond to the F orthogonal subcarriers. The output of the IFFT block may be F time-domain samples that represent the summation of the F orthogonal subcarriers. The F time-domain samples may form a single OFDM symbol. After some processing (e.g., addition of a cyclic prefix) and up-conversion, an OFDM symbol provided by the IFFT block may be transmitted over the air interface on a carrier frequency. The F parallel symbol streams may be mixed using an FFT block before being processed by the IFFT block. This operation produces Discrete Fourier Transform (DFT)-precoded OFDM symbols and may be used by UEs in the uplink to reduce the peak to average power ratio (PAPR). Inverse processing may be performed on the OFDM symbol at a receiver using an FFT block to recover the data mapped to the source symbols.

FIG. 7 illustrates an example configuration of an NR frame into which OFDM symbols are grouped. An NR frame may be identified by a system frame number (SFN). The SFN may repeat with a period of 1024 frames. As illustrated, one NR frame may be 10 milliseconds (ms) in duration and may include 10 subframes that are 1 ms in duration. A subframe may be divided into slots that include, for example, 14 OFDM symbols per slot.

The duration of a slot may depend on the numerology used for the OFDM symbols of the slot. In NR, a flexible numerology is supported to accommodate different cell deployments (e.g., cells with carrier frequencies below 1 GHz up to cells with carrier frequencies in the mm-wave range). A numerology may be defined in terms of subcarrier spacing and cyclic prefix duration. For a numerology in NR, subcarrier spacings may be scaled up by powers of two from a baseline subcarrier spacing of 15 kHz, and cyclic prefix durations may be scaled down by powers of two from a baseline cyclic prefix duration of 4.7 μs. For example, NR defines numerologies with the following subcarrier spacing/cyclic prefix duration combinations: 15 kHz/4.7 μs; 30 kHz/2.3 μs; 60 kHz/1.2 μs; 120 kHz/0.59 μs; and 240 kHz/0.29 μs.

A slot may have a fixed number of OFDM symbols (e.g., 14 OFDM symbols). A numerology with a higher subcarrier spacing has a shorter slot duration and, correspondingly, more slots per subframe. FIG. 7 illustrates this numerology-dependent slot duration and slots-per-subframe transmission structure (the numerology with a subcarrier spacing of 240 kHz is not shown in FIG. 7 for ease of illustration). A subframe in NR may be used as a numerology-independent time reference, while a slot may be used as the unit upon which uplink and downlink transmissions are scheduled. To support low latency, scheduling in NR may be decoupled from the slot duration and start at any OFDM symbol and last for as many symbols as needed for a transmission. These partial slot transmissions may be referred to as mini-slot or subslot transmissions.

FIG. 8 illustrates an example configuration of a slot in the time and frequency domain for an NR carrier. The slot includes resource elements (REs) and resource blocks (RBs). An RE is the smallest physical resource in NR. An RE spans one OFDM symbol in the time domain by one subcarrier in the frequency domain as shown in FIG. 8 . An RB spans twelve consecutive REs in the frequency domain as shown in FIG. 8 . An NR carrier may be limited to a width of 275 RBs or 275×12=3300 subcarriers. Such a limitation, if used, may limit the NR carrier to 50, 100, 200, and 400 MHz for subcarrier spacings of 15, 30, 60, and 120 kHz, respectively, where the 400 MHz bandwidth may be set based on a 400 MHz per carrier bandwidth limit.

FIG. 8 illustrates a single numerology being used across the entire bandwidth of the NR carrier. In other example configurations, multiple numerologies may be supported on the same carrier.

NR may support wide carrier bandwidths (e.g., up to 400 MHz for a subcarrier spacing of 120 kHz). Not all UEs may be able to receive the full carrier bandwidth (e.g., due to hardware limitations). Also, receiving the full carrier bandwidth may be prohibitive in terms of UE power consumption. In an example, to reduce power consumption and/or for other purposes, a UE may adapt the size of the UE's receive bandwidth based on the amount of traffic the UE is scheduled to receive. This is referred to as bandwidth adaptation.

NR defines bandwidth parts (BWPs) to support UEs not capable of receiving the full carrier bandwidth and to support bandwidth adaptation. In an example, a BWP may be defined by a subset of contiguous RBs on a carrier. A UE may be configured (e.g., via RRC layer) with one or more downlink BWPs and one or more uplink BWPs per serving cell (e.g., up to four downlink BWPs and up to four uplink BWPs per serving cell). At a given time, one or more of the configured BWPs for a serving cell may be active. These one or more BWPs may be referred to as active BWPs of the serving cell. When a serving cell is configured with a secondary uplink carrier, the serving cell may have one or more first active BWPs in the uplink carrier and one or more second active BWPs in the secondary uplink carrier.

For unpaired spectra, a downlink BWP from a set of configured downlink BWPs may be linked with an uplink BWP from a set of configured uplink BWPs if a downlink BWP index of the downlink BWP and an uplink BWP index of the uplink BWP are the same. For unpaired spectra, a UE may expect that a center frequency for a downlink BWP is the same as a center frequency for an uplink BWP.

For a downlink BWP in a set of configured downlink BWPs on a primary cell (PCell), a base station may configure a UE with one or more control resource sets (CORESETs) for at least one search space. A search space is a set of locations in the time and frequency domains where the UE may find control information. The search space may be a UE-specific search space or a common search space (potentially usable by a plurality of UEs). For example, a base station may configure a UE with a common search space, on a PCell or on a primary secondary cell (PSCell), in an active downlink BWP.

For an uplink BWP in a set of configured uplink BWPs, a BS may configure a UE with one or more resource sets for one or more PUCCH transmissions. A UE may receive downlink receptions (e.g., PDCCH or PDSCH) in a downlink BWP according to a configured numerology (e.g., subcarrier spacing and cyclic prefix duration) for the downlink BWP. The UE may transmit uplink transmissions (e.g., PUCCH or PUSCH) in an uplink BWP according to a configured numerology (e.g., subcarrier spacing and cyclic prefix length for the uplink BWP).

One or more BWP indicator fields may be provided in Downlink Control Information (DCI). A value of a BWP indicator field may indicate which BWP in a set of configured BWPs is an active downlink BWP for one or more downlink receptions. The value of the one or more BWP indicator fields may indicate an active uplink BWP for one or more uplink transmissions.

A base station may semi-statically configure a UE with a default downlink BWP within a set of configured downlink BWPs associated with a PCell. If the base station does not provide the default downlink BWP to the UE, the default downlink BWP may be an initial active downlink BWP. The UE may determine which BWP is the initial active downlink BWP based on a CORESET configuration obtained using the PBCH.

A base station may configure a UE with a BWP inactivity timer value for a PCell. The UE may start or restart a BWP inactivity timer at any appropriate time. For example, the UE may start or restart the BWP inactivity timer (a) when the UE detects a DCI indicating an active downlink BWP other than a default downlink BWP for a paired spectra operation; or (b) when a UE detects a DCI indicating an active downlink BWP or active uplink BWP other than a default downlink BWP or uplink BWP for an unpaired spectra operation. If the UE does not detect DCI during an interval of time (e.g., 1 ms or 0.5 ms), the UE may run the BWP inactivity timer toward expiration (for example, increment from zero to the BWP inactivity timer value, or decrement from the BWP inactivity timer value to zero). When the BWP inactivity timer expires, the UE may switch from the active downlink BWP to the default downlink BWP.

In an example, a base station may semi-statically configure a UE with one or more BWPs. A UE may switch an active BWP from a first BWP to a second BWP in response to receiving a DCI indicating the second BWP as an active BWP and/or in response to an expiry of the BWP inactivity timer (e.g., if the second BWP is the default BWP).

Downlink and uplink BWP switching (where BWP switching refers to switching from a currently active BWP to a not currently active BWP) may be performed independently in paired spectra. In unpaired spectra, downlink and uplink BWP switching may be performed simultaneously. Switching between configured BWPs may occur based on RRC signaling, DCI, expiration of a BWP inactivity timer, and/or an initiation of random access.

FIG. 9 illustrates an example of bandwidth adaptation using three configured BWPs for an NR carrier. A UE configured with the three BWPs may switch from one BWP to another BWP at a switching point. In the example illustrated in FIG. 9 , the BWPs include: a BWP 902 with a bandwidth of 40 MHz and a subcarrier spacing of 15 kHz; a BWP 904 with a bandwidth of 10 MHz and a subcarrier spacing of 15 kHz; and a BWP 906 with a bandwidth of 20 MHz and a subcarrier spacing of 60 kHz. The BWP 902 may be an initial active BWP, and the BWP 904 may be a default BWP. The UE may switch between BWPs at switching points. In the example of FIG. 9 , the UE may switch from the BWP 902 to the BWP 904 at a switching point 908. The switching at the switching point 908 may occur for any suitable reason, for example, in response to an expiry of a BWP inactivity timer (indicating switching to the default BWP) and/or in response to receiving a DCI indicating BWP 904 as the active BWP. The UE may switch at a switching point 910 from active BWP 904 to BWP 906 in response receiving a DCI indicating BWP 906 as the active BWP. The UE may switch at a switching point 912 from active BWP 906 to BWP 904 in response to an expiry of a BWP inactivity timer and/or in response receiving a DCI indicating BWP 904 as the active BWP. The UE may switch at a switching point 914 from active BWP 904 to BWP 902 in response receiving a DCI indicating BWP 902 as the active BWP.

If a UE is configured for a secondary cell with a default downlink BWP in a set of configured downlink BWPs and a timer value, UE procedures for switching BWPs on a secondary cell may be the same/similar as those on a primary cell. For example, the UE may use the timer value and the default downlink BWP for the secondary cell in the same/similar manner as the UE would use these values for a primary cell.

To provide for greater data rates, two or more carriers can be aggregated and simultaneously transmitted to/from the same UE using carrier aggregation (CA). The aggregated carriers in CA may be referred to as component carriers (CCs). When CA is used, there are a number of serving cells for the UE, one for a CC. The CCs may have three configurations in the frequency domain.

FIG. 10A illustrates the three CA configurations with two CCs. In the intraband, contiguous configuration 1002, the two CCs are aggregated in the same frequency band (frequency band A) and are located directly adjacent to each other within the frequency band. In the intraband, non-contiguous configuration 1004, the two CCs are aggregated in the same frequency band (frequency band A) and are separated in the frequency band by a gap. In the interband configuration 1006, the two CCs are located in frequency bands (frequency band A and frequency band B).

In an example, up to 32 CCs may be aggregated. The aggregated CCs may have the same or different bandwidths, subcarrier spacing, and/or duplexing schemes (TDD or FDD). A serving cell for a UE using CA may have a downlink CC. For FDD, one or more uplink CCs may be optionally configured for a serving cell. The ability to aggregate more downlink carriers than uplink carriers may be useful, for example, when the UE has more data traffic in the downlink than in the uplink.

When CA is used, one of the aggregated cells for a UE may be referred to as a primary cell (PCell). The PCell may be the serving cell that the UE initially connects to at RRC connection establishment, reestablishment, and/or handover. The PCell may provide the UE with NAS mobility information and the security input. UEs may have different PCells. In the downlink, the carrier corresponding to the PCell may be referred to as the downlink primary CC (DL PCC). In the uplink, the carrier corresponding to the PCell may be referred to as the uplink primary CC (UL PCC). The other aggregated cells for the UE may be referred to as secondary cells (SCells). In an example, the SCells may be configured after the PCell is configured for the UE. For example, an SCell may be configured through an RRC Connection Reconfiguration procedure. In the downlink, the carrier corresponding to an SCell may be referred to as a downlink secondary CC (DL SCC). In the uplink, the carrier corresponding to the SCell may be referred to as the uplink secondary CC (UL SCC).

Configured SCells for a UE may be activated and deactivated based on, for example, traffic and channel conditions. Deactivation of an SCell may mean that PDCCH and PDSCH reception on the SCell is stopped and PUSCH, SRS, and CQI transmissions on the SCell are stopped. Configured SCells may be activated and deactivated using a MAC CE with respect to FIG. 4B. For example, a MAC CE may use a bitmap (e.g., one bit per SCell) to indicate which SCells (e.g., in a subset of configured SCells) for the UE are activated or deactivated. Configured SCells may be deactivated in response to an expiration of an SCell deactivation timer (e.g., one SCell deactivation timer per SCell).

Downlink control information, such as scheduling assignments and scheduling grants, for a cell may be transmitted on the cell corresponding to the assignments and grants, which is known as self-scheduling. The DCI for the cell may be transmitted on another cell, which is known as cross-carrier scheduling. Uplink control information (e.g., HARQ acknowledgments and channel state feedback, such as CQI, PMI, and/or RI) for aggregated cells may be transmitted on the PUCCH of the PCell. For a larger number of aggregated downlink CCs, the PUCCH of the PCell may become overloaded. Cells may be divided into multiple PUCCH groups.

FIG. 10B illustrates an example of how aggregated cells may be configured into one or more PUCCH groups. A PUCCH group 1010 and a PUCCH group 1050 may include one or more downlink CCs, respectively. In the example of FIG. 10B, the PUCCH group 1010 includes three downlink CCs: a PCell 1011, an SCell 1012, and an SCell 1013. The PUCCH group 1050 includes three downlink CCs in the present example: a PCell 1051, an SCell 1052, and an SCell 1053. One or more uplink CCs may be configured as a PCell 1021, an SCell 1022, and an SCell 1023. One or more other uplink CCs may be configured as a primary Scell (PSCell) 1061, an SCell 1062, and an SCell 1063. Uplink control information (UCI) related to the downlink CCs of the PUCCH group 1010, shown as UCI 1031, UCI 1032, and UCI 1033, may be transmitted in the uplink of the PCell 1021. Uplink control information (UCI) related to the downlink CCs of the PUCCH group 1050, shown as UCI 1071, UCI 1072, and UCI 1073, may be transmitted in the uplink of the PSCell 1061. In an example, if the aggregated cells depicted in FIG. 10B were not divided into the PUCCH group 1010 and the PUCCH group 1050, a single uplink PCell to transmit UCI relating to the downlink CCs, and the PCell may become overloaded. By dividing transmissions of UCI between the PCell 1021 and the PSCell 1061, overloading may be prevented.

A cell, comprising a downlink carrier and optionally an uplink carrier, may be assigned with a physical cell ID and a cell index. The physical cell ID or the cell index may identify a downlink carrier and/or an uplink carrier of the cell, for example, depending on the context in which the physical cell ID is used. A physical cell ID may be determined using a synchronization signal transmitted on a downlink component carrier. A cell index may be determined using RRC messages. In the disclosure, a physical cell ID may be referred to as a carrier ID, and a cell index may be referred to as a carrier index. For example, when the disclosure refers to a first physical cell ID for a first downlink carrier, the disclosure may mean the first physical cell ID is for a cell comprising the first downlink carrier. The same/similar concept may apply to, for example, a carrier activation. When the disclosure indicates that a first carrier is activated, the specification may mean that a cell comprising the first carrier is activated.

In CA, a multi-carrier nature of a PHY may be exposed to a MAC. In an example, a HARQ entity may operate on a serving cell. A transport block may be generated per assignment/grant per serving cell. A transport block and potential HARQ retransmissions of the transport block may be mapped to a serving cell.

FIG. 11A and FIG. 11B illustrate packet flows employing dual connectivity (DC). DC is referred to as at least one of multi-connectivity, tight interworking, multi-radio dual connectivity (MR-DC), E-UTRA-NR dual connectivity (EN-DC), NG-RAN E-UTRA-NR dual connectivity (NGEN-DC), NR-E-UTRA dual connectivity (NE-DC), NR-NR dual connectivity (NR-DC), E-UTRA dual connectivity, and/or the like. In EN-DC, a UE may be connected to at least one eNB that may act as a master node (MN) and at least one en-gNB that may act as a secondary node (SN). The at least one eNB may be connected to an evolved packet core (EPC) via an S1 interface and to the at least one en-gNB via an X2 interface. In NGEN-DC, a UE may be connected to at least one ng-eNB that may act as an MN and at least one gNB that may act as an SN. The at least one ng-eNB may be connected to a 5G-CN and the at least one gNB may be connected to the at least one ng-eNB via an Xn interface. In NE-DC, a UE may be connected to at least one gNB that may act as an MN and at least one ng-eNB that may act as an SN. The at least one gNB may be connected to a 5G-CN via an NG interface (e.g., N2 interface and/or N3 interface) and the ng-eNB may be connected to the gNB via an Xn interface. In NR-DC, a UE may be connected to at least one gNB that may act as an MN and at least one another gNB that may act as an SN. The at least one gNB acting as an MN may be connected to a 5G-CN via an NG interface and to the at least one another gNB acting as an SN via an Xn interface. In E-UTRA dual connectivity, a UE may be connected to at least one eNB that may act as an MN and at least one another eNB that may act as an SN. The at least one eNB acting as an MN may be connected to an EPC via an S1 interface and to the at least one another eNB acting as an SN via an X2 interface.

FIG. 11A illustrates an example diagram of a protocol structure of a UE 1102 with carrier aggregation (CA) and/or dual connectivity (DC). In dual connectivity, the UE 1102 may be connected to one master node (MN) and one or more secondary nodes (SNs).

FIG. 11B illustrates an example diagram of a protocol structure of multiple base stations with CA and/or DC. The multiple base stations may comprise an MN 1130 (e.g., a master base station, a master gNB, a master eNB, and/or the like) and an SN 1150 (e.g., a secondary base station, a secondary gNB, a secondary eNB, and/or the like). The MN 1130 and SN 1150 may cooperate to communicate with, for example, the UE 1102 depicted in FIG. 11A.

The UE 1102 may support multiple reception/transmission functions in an RRC connected state. When dual connectivity is configured for the UE 1102, the UE 1102 may be configured to utilize radio resources provided by multiple schedulers of multiple base stations (e.g., the MN 1130 and SN 1150 depicted in FIG. 11B). The multiple base stations may be inter-connected via a non-ideal or ideal backhaul (e.g., Xn interface, X2 interface, and/or the like). In an example, the MN 1130 may provide a master cell group (MCG) comprising a primary cell and/or one or more secondary cells for the UE 1102. The SN 1150 may provide a secondary cell group (SCG) comprising a primary secondary cell (PSCell) and/or one or more secondary cells for the UE 1102. In an example, the MCG may be provided by a master base station distributed unit (DU) (e.g., a gNB-DU), and the SCG may be provided by a secondary base station DU. A base station central unit (CU) (e.g., a gNB-CU) may provide an RRC layer, an SDAP layer, and/or a PDCP layer that the master base station DU and the secondary base station DU may use to communicate with the UE 1102.

In dual connectivity, a radio protocol architecture that a bearer employs may depend on how the bearer is set up. In an example, three type of bearer setup options may be supported: an MCG bearer, an SCG bearer, and/or a split bearer. The UE 1102 may receive/transmit packets of the MCG bearer via one or more cells of the MCG, and/or may receive/transmits packets of the SCG bearer via one or more cells of the SCG. Dual connectivity may be described as having at least one bearer configured to use radio resources provided by the SN 1150. Dual connectivity may or may not be configured/implemented in some of the example embodiments.

As shown in the example of FIG. 11A, the UE 1102 may transmit and/or receive: (a) packets of an MCG bearer via an SDAP 1110, a PDCP 1111 (e.g., NR PDCP, E-UTRA PDCP), an RLC 1114 (e.g., MN RLC), and a MAC 1118 (e.g., MN MAC); (b) packets of a split bearer via the SDAP 1110, a PDCP 1112 (e.g., NR PDCP, E-UTRA PDCP), one of a master or secondary RLC (e.g., an MN RLC 1115 or an SN RLC 1116), and one of a master or secondary MAC (e.g., the MN MAC 1118 or an SN MAC 1119); and/or (c) packets of an SCG bearer via the SDAP 1110, a PDCP 1113 (e.g., NR PDCP, E-UTRA PDCP), an RLC (e.g., an SN RLC 1117), and the SN MAC 1119.

As shown in the example of FIG. 11B, the MN 1130 may transmit and/or receive: (a) packets of an MCG bearer via an SDAP 1120, a PDCP 1121 (e.g., NR PDCP, E-UTRA PDCP), an MN RLC 1124, and an MN MAC 1128; (b) packets of an SCG bearer via the SDAP 1120, a PDCP 1122 (e.g., NR PDCP, E-UTRA PDCP), an SN RLC 1146, and an SN MAC 1148; and/or (c) packets of a split bearer via the SDAP 1120, a PDCP 1123 (e.g., NR PDCP, E-UTRA PDCP), an RLC (e.g., an MN RLC 1126 or an SN RLC 1144), and a MAC (e.g., the MN MAC 1128 or an SN MAC 1148). As shown in the example of FIG. 11B, the SN 1150 may transmit and/or receive: (a) packets of an MCG bearer via an SDAP 1140, a PDCP 1142 (e.g., NR PDCP, E-UTRA PDCP), an MN RLC 1125, and the MN MAC 1128; (b) packets of an SCG bearer via the SDAP 1140, a PDCP 1143 (e.g., NR PDCP, E-UTRA PDCP), an SN RLC 1147, and the SN MAC 1148; and/or (c) packets of a split bearer via the SDAP 1140, a secondary node PDCP layer 1141 (e.g., NR PDCP, E-UTRA PDCP), an RLC (e.g., an MN RLC 1127 or an SN RLC 1145), and a MAC (e.g., the MN MAC 1128 or the SN MAC 1148).

In dual connectivity, the UE 1102 may configure multiple MAC entities: one MAC entity for the MN 1130 (e.g., the MN MAC 1118), and one or more other MAC entities for the SN 1150 (e.g., the SN MAC 1119). A configured set of serving cells for the UE 1102 may comprise two subsets: an MCG comprising serving cells of a master base station (e.g., the MN 1130), and one or more SCGs comprising serving cells of one or more secondary base stations (e.g., the SN 1150). For an SCG, at least one cell has a configured UL CC. At least one cell of the SCG, which may be referred to as a primary secondary cell (e.g., a PSCell, PCell of SCG, or in some contexts PCell), is configured with PUCCH resources. When an SCG is configured, there may be at least one SCG bearer and/or at least one split bearer. Upon detection of a physical layer problem or a random access problem on a PSCell, a number of RLC retransmissions associated with the SCG being reached, or an access problem on a PSCell during a SCG addition or a SCG change, an appropriate action may be taken. For example, the UE 1102 may elect not to trigger an RRC connection re-establishment procedure, UL transmissions towards cells of the SCG may be stopped, the MN 1130 may be informed by the UE 1102 of an SCG failure type, and/or a DL data transfer via the MN 1130 for a split bearer may be maintained. An RLC Acknowledged Mode (AM) bearer may be configured for a split bearer. A PCell and/or a PSCell may not be de-activated during an SCG being configured. A PSCell may be changed with an SCG change procedure (e.g., with a security key change and a RACH procedure). A bearer type switching between a split bearer and a SCG bearer or simultaneous configuration of a SCG and a split bearer for a bearer may or may not be supported.

When the UE 1102 is configured for dual connectivity, the MN 1130 and/or the SN 1150 may maintain Radio Resource Management (RRM) measurement configurations of the UE 1102. The MN 1130 may determine (e.g., based on received measurement reports, traffic conditions, and/or bearer types) to request that the SN 1150 provide resources (e.g., serving cells) for the UE 1102. Upon receiving a request from the MN 1130, the SN 1150 may create or modify a container that may cause configuration of serving cells for the UE 1102, or, decline the request based on a determination that sufficient resources are not available. For UE capability coordination, the MN 1130 may provide at least a portion of an AS configuration and/or an indicator of the UE capabilities to the SN 1150. The MN 1130 and the SN 1150 may exchange information about a configuration of the UE 1102 by employing RRC containers (e.g., inter-node messages) carried via Xn and/or X2 messages. The SN 1150 may initiate a self-reconfiguration for existing serving cells. The SN 1150 may determine which cell is a PSCell within the SCG. The MN 1130 may or may not update content of RRC configurations provided by the SN 1150. In the event that an SCG and/or SCG Scell is added, the MN 1130 may provide recent (e.g., the latest) measurement results of the UE 1102 relating to the SCG cell(s). The MN 1130 may receive information relating to a system frame number (SFN) and/or subframe offset of the SN 1150 from an OAM and/or from the SN 1150 itself via an Xn/X2 interface (e.g., for a purpose of DRX alignment and/or identification of a measurement gap). The SN 1150 may receive similar information relating to the MN 1130 in substantially the same/similar manner. When adding a new SCG SCell, dedicated RRC signaling may be used for sending required system information of a new SCG SCell as for CA (e.g., except for an SFN acquired from a MIB of a PSCell of the SCG).

FIG. 12 illustrates an example of a transmitter 1210 and a receiver 1220 having multiple antennas. The transmitter 1210 in the example of FIG. 12 may comprise a first physical antenna 1211, a second physical antenna 1212, a third physical antenna 1213, and a fourth physical antenna 1214. The receiver 1220 in the example of FIG. 12 may comprise a first physical antenna 1221, a second physical antenna 1222, a third physical antenna 1223, and a fourth physical antenna 1224. The transmitter 1210 may correspond to a base station or a UE. Similarly, the receiver 1220 may correspond to a base station or a UE. A UE (wireless device) may comprise a receiver and/or a transmitter. A base station may comprise a receiver and/or a transmitter. A UE may comprise at least one processor, and memory storing instructions that, when executed by the one or more processors, cause the wireless device to perform certain processes according to example embodiments. A base station may comprise at least one processor, and memory storing instructions that, when executed by the one or more processors, cause the base station to perform certain processes according to example embodiments. Network nodes, for example, a base station distributed unit and a base station central unit, may comprise at least one processor, and memory storing instructions that, when executed by the network node, cause the network node to perform certain processes according to example embodiments. A network node (e.g. a UE, base station, BS-DU, BS-CU) may comprise one or more interfaces for communication with other nodes.

The transmitter 1210 and the receiver 1220 may communicate using one or more channels. In an example, a channel may be established using a single physical antenna associated with the transmitter 1210 (for example, the physical antenna 1211) and a single physical antenna associated with the receiver 1220 (for example, the physical antenna 1221). In an example, the transmitter 1210 and/or the receiver 1220 may use a plurality of antennas to form the channel. For example, the transmitter 1210 may use one or more of the physical antennas 1211-1214 to transmit the same/similar signal, and by varying the amplitude and/or phase of the respective signals, the physical antennas 1211-1214 may form a transmission beam that transmits the signal in a direction (for example, the direction of the receiver 1220). The transmission beam can be made narrower by using a larger number of physical antennas. In a reciprocal manner, the plurality of physical antennas at the receiver side may form a reception beam that receives from a direction.

A channel may be established between the transmitter 1210 and the receiver 1220 using any subset of the physical antennas 1211-1214 and any subset of the physical antennas 1221-1224. An antenna port may correspond to the subset of physical antennas associated with a channel. A single physical antenna may be associated with a plurality of channels and/or a plurality of antenna ports. For example, the transmitter 1210 may use the physical antenna 1211 by itself to form a first channel in which it transmits a first signal throughout a coverage area of the transmitter 1210. The transmitter 1210 may use one or more of the physical antennas 1211-1214 to form a second channel in which it transmits a second signal in a direction using a transmission beam. From the perspective of the receiver 1220, the first channel is formed by a first antenna port of the transmitter 1210 and the second channel is formed by a second antenna port of the transmitter 1210.

An antenna port is defined such that the channel over which a symbol on the antenna port is conveyed can be inferred from the channel over which another symbol on the same antenna port is conveyed. If a first symbol and a second symbol are transmitted on the same antenna port, the receiver may infer the channel (e.g., fading gain, multipath delay, and/or the like) for conveying the second symbol on the antenna port, from the channel for conveying the first symbol on the antenna port. A first antenna port and a second antenna port may be referred to as quasi co-located (QCLed) if one or more large-scale properties of the channel over which a first symbol on the first antenna port is conveyed may be inferred from the channel over which a second symbol on a second antenna port is conveyed. The one or more large-scale properties may comprise at least one of: a delay spread; a Doppler spread; a Doppler shift; an average gain; an average delay; and/or spatial Receiving (Rx) parameters.

Channels that use beamforming require beam management. Beam management may comprise beam measurement, beam selection, and beam indication. A beam may be associated with one or more reference signals. For example, a beam may be identified by one or more beamformed reference signals. The UE may perform downlink beam measurement based on downlink reference signals (e.g., a channel state information reference signal (CSI-RS)) and generate a beam measurement report. The UE may perform the downlink beam measurement procedure after an RRC connection is set up with a base station.

FIG. 13 illustrates an example of channel state information reference signals (CSI-RSs) that are mapped in the time and frequency domains. A square shown in FIG. 13 may span a resource block (RB) within a bandwidth of a cell. A base station may transmit one or more RRC messages comprising CSI-RS resource configuration parameters indicating one or more CSI-RSs. One or more of the following parameters may be configured by higher layer signaling (e.g., RRC and/or MAC signaling) for a CSI-RS resource configuration: a CSI-RS resource configuration identity, a number of CSI-RS ports, a CSI-RS configuration (e.g., symbol and resource element (RE) locations in a subframe), a CSI-RSsubframe configuration (e.g., subframe location, offset, and periodicity in a radio frame), a CSI-RS power parameter, a CSI-RSsequence parameter, a code division multiplexing (CDM) type parameter, a frequency density, a transmission comb, quasi co-location (QCL) parameters (e.g., QCL-scramblingidentity, crs-portscount, mbsfn-subframeconfiglist, csi-rs-configZPid, qcl-csi-rs-configNZPid), and/or other radio resource parameters.

The three beams illustrated in FIG. 13 may be configured for a UE in a UE-specific configuration. Three beams are illustrated in FIG. 13 (beam #1, beam #2, and beam #3), more or fewer beams may be configured. Beam #1 may be allocated with CSI-RS 1301 that may be transmitted in one or more subcarriers in an RB of a first symbol. Beam #2 may be allocated with CSI-RS 1302 that may be transmitted in one or more subcarriers in an RB of a second symbol. Beam #3 may be allocated with CSI-RS 1303 that may be transmitted in one or more subcarriers in an RB of a third symbol. By using frequency division multiplexing (FDM), a base station may use other subcarriers in a same RB (for example, those that are not used to transmit CSI-RS 1301) to transmit another CSI-RS associated with a beam for another UE. By using time domain multiplexing (TDM), beams used for the UE may be configured such that beams for the UE use symbols from beams of other UEs.

CSI-RSs such as those illustrated in FIG. 13 (e.g., CSI-RS 1301, 1302, 1303) may be transmitted by the base station and used by the UE for one or more measurements. For example, the UE may measure a reference signal received power (RSRP) of configured CSI-RS resources. The base station may configure the UE with a reporting configuration and the UE may report the RSRP measurements to a network (for example, via one or more base stations) based on the reporting configuration. In an example, the base station may determine, based on the reported measurement results, one or more transmission configuration indication (TCI) states comprising a number of reference signals. In an example, the base station may indicate one or more TCI states to the UE (e.g., via RRC signaling, a MAC CE, and/or a DCI). The UE may receive a downlink transmission with a receive (Rx) beam determined based on the one or more TCI states. In an example, the UE may or may not have a capability of beam correspondence. If the UE has the capability of beam correspondence, the UE may determine a spatial domain filter of a transmit (Tx) beam based on a spatial domain filter of the corresponding Rx beam. If the UE does not have the capability of beam correspondence, the UE may perform an uplink beam selection procedure to determine the spatial domain filter of the Tx beam. The UE may perform the uplink beam selection procedure based on one or more sounding reference signal (SRS) resources configured to the UE by the base station. The base station may select and indicate uplink beams for the UE based on measurements of the one or more SRS resources transmitted by the UE.

In a beam management procedure, a UE may assess (e.g., measure) a channel quality of one or more beam pair links, a beam pair link comprising a transmitting beam transmitted by a base station and a receiving beam received by the UE. Based on the assessment, the UE may transmit a beam measurement report indicating one or more beam pair quality parameters comprising, e.g., one or more beam identifications (e.g., a beam index, a reference signal index, or the like), RSRP, a precoding matrix indicator (PMI), a channel quality indicator (CQI), and/or a rank indicator (RI).

FIG. 14A illustrates examples of three downlink beam management procedures: P1, P2, and P3. Procedure P1 may enable a UE measurement on transmit (Tx) beams of a transmission reception point (TRP) (or multiple TRPs), e.g., to support a selection of one or more base station Tx beams and/or UE Rx beams (shown as ovals in the top row and bottom row, respectively, of P1). Beamforming at a TRP may comprise a Tx beam sweep for a set of beams (shown, in the top rows of P1 and P2, as ovals rotated in a counter-clockwise direction indicated by the dashed arrow). Beamforming at a UE may comprise an Rx beam sweep for a set of beams (shown, in the bottom rows of P1 and P3, as ovals rotated in a clockwise direction indicated by the dashed arrow). Procedure P2 may be used to enable a UE measurement on Tx beams of a TRP (shown, in the top row of P2, as ovals rotated in a counter-clockwise direction indicated by the dashed arrow). The UE and/or the base station may perform procedure P2 using a smaller set of beams than is used in procedure P1, or using narrower beams than the beams used in procedure P1. This may be referred to as beam refinement. The UE may perform procedure P3 for Rx beam determination by using the same Tx beam at the base station and sweeping an Rx beam at the UE.

FIG. 14B illustrates examples of three uplink beam management procedures: U1, U2, and U3. Procedure U1 may be used to enable a base station to perform a measurement on Tx beams of a UE, e.g., to support a selection of one or more UE Tx beams and/or base station Rx beams (shown as ovals in the top row and bottom row, respectively, of U1). Beamforming at the UE may include, e.g., a Tx beam sweep from a set of beams (shown in the bottom rows of U1 and U3 as ovals rotated in a clockwise direction indicated by the dashed arrow). Beamforming at the base station may include, e.g., an Rx beam sweep from a set of beams (shown, in the top rows of U1 and U2, as ovals rotated in a counter-clockwise direction indicated by the dashed arrow). Procedure U2 may be used to enable the base station to adjust its Rx beam when the UE uses a fixed Tx beam. The UE and/or the base station may perform procedure U2 using a smaller set of beams than is used in procedure P1, or using narrower beams than the beams used in procedure P1. This may be referred to as beam refinement The UE may perform procedure U3 to adjust its Tx beam when the base station uses a fixed Rx beam.

A UE may initiate a beam failure recovery (BFR) procedure based on detecting a beam failure. The UE may transmit a BFR request (e.g., a preamble, a UCI, an SR, a MAC CE, and/or the like) based on the initiating of the BFR procedure. The UE may detect the beam failure based on a determination that a quality of beam pair link(s) of an associated control channel is unsatisfactory (e.g., having an error rate higher than an error rate threshold, a received signal power lower than a received signal power threshold, an expiration of a timer, and/or the like).

The UE may measure a quality of a beam pair link using one or more reference signals (RSs) comprising one or more SS/PBCH blocks, one or more CSI-RS resources, and/or one or more demodulation reference signals (DMRSs). A quality of the beam pair link may be based on one or more of a block error rate (BLER), an RSRP value, a signal to interference plus noise ratio (SINR) value, a reference signal received quality (RSRQ) value, and/or a CSI value measured on RS resources. The base station may indicate that an RS resource is quasi co-located (QCLed) with one or more DM-RSs of a channel (e.g., a control channel, a shared data channel, and/or the like). The RS resource and the one or more DMRSs of the channel may be QCLed when the channel characteristics (e.g., Doppler shift, Doppler spread, average delay, delay spread, spatial Rx parameter, fading, and/or the like) from a transmission via the RS resource to the UE are similar or the same as the channel characteristics from a transmission via the channel to the UE.

FIG. 15 illustrates an example of a BFR procedure. A UE may receive one or more RRC messages comprising BFR parameters for a serving cell (e.g., a PCell, an SCell, and/or an SPCell). The UE may detect at least one beam failure according to at least one of the BFR parameters. The UE may initiate the BFR procedure (e.g., random-access channel based, physical uplink control channel based, physical uplink shared channel based) based on the detecting the at least one beam failure. The UE may start a first timer (e.g., indicated by the BFR parameters) based on the initiating the BFR procedure. The first timer may be used to determine how long the UE may find a candidate beam and may be referred to as a beam failure recovery timer (e.g., beamFailureRecoveryTimer). The UE may determine an RS based on the BFR parameters for the BFR procedure. The UE may transmit at least one uplink signal, for the BFR procedure, to a gNB associated with the serving cell in response to the determining the RS. The UE may start a response window in response to transmitting the at least one uplink signal. In an example, the response window may be a second timer with a value indicated by the BFR parameters. When the response window is running, the UE may monitor, for a DCI, a PDCCH in a control resource set (CORESET) indicated by the BFR parameters. The CORESET may be dedicated to the UE. The UE may receive the DCI via the PDCCH in the CORESET when the response window is running. The UE may consider the BFR procedure successfully completed based on receiving the DCI via the PDCCH in the CORESET. The UE may stop the first timer and/or stop the response window in response to the BFR procedure being completed successfully. In an example, the DCI may be an uplink grant or a downlink assignment for the serving cell.

In an example, the UE may not receive the DCI before the response window expires. If the DCI is not received during the response window, the UE may perform one or more actions comprising at least one of: a retransmission of at least one uplink signal for the BFR procedure; re-starting the response window; or monitoring the PDCCH in the CORESET. The UE may repeat the one or more actions until the BFR procedure is complete.

The UE may perform one or more retransmissions of at least one uplink signal for the BFR procedure until a threshold number of re-transmissions is reached. The threshold number of re-transmissions may be indicated by the BFR parameters. When the threshold number of retransmissions is reached, the UE determines that the BFR procedure is complete. The UE may indicate to higher layers (e.g., RRC and/or MAC) of the UE that the BFR procedure is unsuccessful (e.g., by indicating to the higher layers that the threshold number of re-transmissions is reached).

In the downlink, a base station may transmit (e.g., unicast, multicast, and/or broadcast) one or more Reference Signals (RSs) to a UE (e.g., PSS, SSS, CSI-RS, DMRS, and/or PT-RS, as shown in FIG. 5A). In the uplink, the UE may transmit one or more RSs to the base station (e.g., DMRS, PT-RS, and/or SRS, as shown in FIG. 5B). The PSS and the SSS may be transmitted by the base station and used by the UE to synchronize the UE to the base station. As shown in FIG. 15 , the PSS and the SSS may be provided in a synchronization signal (SS)/physical broadcast channel (PBCH) block that includes the PSS, the SSS, and the PBCH. The base station may periodically transmit a burst of SS/PBCH blocks.

FIG. 16 illustrates an example of an SS/PBCH block's structure and location. A burst of SS/PBCH blocks may include one or more SS/PBCH blocks (e.g., 4 SS/PBCH blocks, as shown in FIG. 16 ). Bursts may be transmitted periodically (e.g., every 2 frames or 20 ms, as shown in FIG. 16 ). A burst may be restricted to a half-frame (e.g., a first half-frame having a duration of 5 ms, as shown in FIG. 16 ). It will be understood that FIG. 16 is an example, and that these parameters (number of SS/PBCH blocks per burst, periodicity of bursts, position of burst within the frame) may be configured based on, for example: a carrier frequency of a cell in which the SS/PBCH block is transmitted; a numerology or subcarrier spacing of the cell; a configuration by the network (e.g., using RRC signaling); or any other suitable factor. In an example, the UE may assume a subcarrier spacing for the SS/PBCH block based on the carrier frequency being monitored, unless the radio network configured the UE to assume a different subcarrier spacing.

The SS/PBCH block may span one or more OFDM symbols in the time domain (e.g., 4 OFDM symbols, as shown in the example of FIG. 16 ) and may span one or more subcarriers in the frequency domain (e.g., 240 contiguous subcarriers). The PSS, the SSS, and the PBCH may have a common center frequency. The PSS may be transmitted first and may span, for example, 1 OFDM symbol and 127 subcarriers. The SSS may be transmitted after the PSS (e.g., two symbols later) and may span 1 OFDM symbol and 127 subcarriers. The PBCH may be transmitted after the PSS (e.g., across the next 3 OFDM symbols) and may span 240 subcarriers.

The location of the SS/PBCH block in the time and frequency domains may not be known to the UE (e.g., if the UE is searching for the cell). To find and select the cell, the UE may monitor a carrier for the PSS. For example, the UE may monitor a frequency location within the carrier. If the PSS is not found after a certain duration (e.g., 20 ms), the UE may search for the PSS at a different frequency location within the carrier, as indicated by a synchronization raster. If the PSS is found at a location in the time and frequency domains, the UE may determine, based on a known structure of the SS/PBCH block, the locations of the SSS and the PBCH, respectively. The SS/PBCH block may be a cell-defining SS block (CD-SSB). In an example, a primary cell may be associated with a CD-SSB. The CD-SSB may be located on a synchronization raster. In an example, a cell selection/search and/or reselection may be based on the CD-SSB.

The SS/PBCH block may be used by the UE to determine one or more parameters of the cell. For example, the UE may determine a physical cell identifier (PCI) of the cell based on the sequences of the PSS and the SSS, respectively. The UE may determine a location of a frame boundary of the cell based on the location of the SS/PBCH block. For example, the SS/PBCH block may indicate that it has been transmitted in accordance with a transmission pattern, wherein a SS/PBCH block in the transmission pattern is a known distance from the frame boundary.

The PBCH may use a QPSK modulation and may use forward error correction (FEC). The FEC may use polar coding. One or more symbols spanned by the PBCH may carry one or more DMRSs for demodulation of the PBCH. The PBCH may include an indication of a current system frame number (SFN) of the cell and/or a SS/PBCH block timing index. These parameters may facilitate time synchronization of the UE to the base station. The PBCH may include a master information block (MIB) used to provide the UE with one or more parameters. The MIB may be used by the UE to locate remaining minimum system information (RMSI) associated with the cell. The RMSI may include a System Information Block Type 1 (SIB1). The SIB1 may contain information needed by the UE to access the cell. The UE may use one or more parameters of the MIB to monitor PDCCH, which may be used to schedule PDSCH. The PDSCH may include the SIB1. The SIB1 may be decoded using parameters provided in the MIB. The PBCH may indicate an absence of SIB1. Based on the PBCH indicating the absence of SIB1, the UE may be pointed to a frequency. The UE may search for an SS/PBCH block at the frequency to which the UE is pointed.

The UE may assume that one or more SS/PBCH blocks transmitted with a same SS/PBCH block index are quasi co-located (QCLed) (e.g., having the same/similar Doppler spread, Doppler shift, average gain, average delay, and/or spatial Rx parameters). The UE may not assume QCL for SS/PBCH block transmissions having different SS/PBCH block indices.

SS/PBCH blocks (e.g., those within a half-frame) may be transmitted in spatial directions (e.g., using different beams that span a coverage area of the cell). In an example, a first SS/PBCH block may be transmitted in a first spatial direction using a first beam, and a second SS/PBCH block may be transmitted in a second spatial direction using a second beam.

In an example, within a frequency span of a carrier, a base station may transmit a plurality of SS/PBCH blocks. In an example, a first PCI of a first SS/PBCH block of the plurality of SS/PBCH blocks may be different from a second PCI of a second SS/PBCH block of the plurality of SS/PBCH blocks. The PCIs of SS/PBCH blocks transmitted in different frequency locations may be different or the same.

The CSI-RS may be transmitted by the base station and used by the UE to acquire channel state information (CSI). The base station may configure the UE with one or more CSI-RSs for channel estimation or any other suitable purpose. The base station may configure a UE with one or more of the same/similar CSI-RSs. The UE may measure the one or more CSI-RSs. The UE may estimate a downlink channel state and/or generate a CSI report based on the measuring of the one or more downlink CSI-RSs. The UE may provide the CSI report to the base station. The base station may use feedback provided by the UE (e.g., the estimated downlink channel state) to perform link adaptation.

The base station may semi-statically configure the UE with one or more CSI-RS resource sets. A CSI-RS resource may be associated with a location in the time and frequency domains and a periodicity. The base station may selectively activate and/or deactivate a CSI-RS resource. The base station may indicate to the UE that a CSI-RS resource in the CSI-RS resource set is activated and/or deactivated.

The base station may configure the UE to report CSI measurements. The base station may configure the UE to provide CSI reports periodically, aperiodically, or semi-persistently. For periodic CSI reporting, the UE may be configured with a timing and/or periodicity of a plurality of CSI reports. For aperiodic CSI reporting, the base station may request a CSI report. For example, the base station may command the UE to measure a configured CSI-RS resource and provide a CSI report relating to the measurements. For semi-persistent CSI reporting, the base station may configure the UE to transmit periodically, and selectively activate or deactivate the periodic reporting. The base station may configure the UE with a CSI-RS resource set and CSI reports using RRC signaling.

The CSI-RS configuration may comprise one or more parameters indicating, for example, up to 32 antenna ports. The UE may be configured to employ the same OFDM symbols for a downlink CSI-RS and a control resource set (CORESET) when the downlink CSI-RS and CORESET are spatially QCLed and resource elements associated with the downlink CSI-RS are outside of the physical resource blocks (PRBs) configured for the CORESET. The UE may be configured to employ the same OFDM symbols for downlink CSI-RS and SS/PBCH blocks when the downlink CSI-RS and SS/PBCH blocks are spatially QCLed and resource elements associated with the downlink CSI-RS are outside of PRBs configured for the SS/PBCH blocks.

Downlink DMRSs may be transmitted by a base station and used by a UE for channel estimation. For example, the downlink DMRS may be used for coherent demodulation of one or more downlink physical channels (e.g., PDSCH). An NR network may support one or more variable and/or configurable DMRS patterns for data demodulation. At least one downlink DMRS configuration may support a front-loaded DMRS pattern. A front-loaded DMRS may be mapped over one or more OFDM symbols (e.g., one or two adjacent OFDM symbols). A base station may semi-statically configure the UE with a number (e.g. a maximum number) of front-loaded DMRS symbols for PDSCH. A DMRS configuration may support one or more DMRS ports. For example, for single user-MIMO, a DMRS configuration may support up to eight orthogonal downlink DMRS ports per UE. For multiuser-MIMO, a DMRS configuration may support up to 4 orthogonal downlink DMRS ports per UE. A radio network may support (e.g., at least for CP-OFDM) a common DMRS structure for downlink and uplink, wherein a DMRS location, a DMRS pattern, and/or a scrambling sequence may be the same or different. The base station may transmit a downlink DMRS and a corresponding PDSCH using the same precoding matrix. The UE may use the one or more downlink DMRSs for coherent demodulation/channel estimation of the PDSCH.

In an example, a transmitter (e.g., a base station) may use a precoder matrices for a part of a transmission bandwidth. For example, the transmitter may use a first precoder matrix for a first bandwidth and a second precoder matrix for a second bandwidth. The first precoder matrix and the second precoder matrix may be different based on the first bandwidth being different from the second bandwidth. The UE may assume that a same precoding matrix is used across a set of PRBs. The set of PRBs may be denoted as a precoding resource block group (PRG).

A PDSCH may comprise one or more layers. The UE may assume that at least one symbol with DMRS is present on a layer of the one or more layers of the PDSCH. A higher layer may configure up to 3 DMRSs for the PDSCH.

Downlink PT-RS may be transmitted by a base station and used by a UE for phase-noise compensation. Whether a downlink PT-RS is present or not may depend on an RRC configuration. The presence and/or pattern of the downlink PT-RS may be configured on a UE-specific basis using a combination of RRC signaling and/or an association with one or more parameters employed for other purposes (e.g., modulation and coding scheme (MCS)), which may be indicated by DCI. When configured, a dynamic presence of a downlink PT-RS may be associated with one or more DCI parameters comprising at least MCS. An NR network may support a plurality of PT-RS densities defined in the time and/or frequency domains. When present, a frequency domain density may be associated with at least one configuration of a scheduled bandwidth. The UE may assume a same precoding for a DMRS port and a PT-RS port. A number of PT-RS ports may be fewer than a number of DMRS ports in a scheduled resource. Downlink PT-RS may be confined in the scheduled time/frequency duration for the UE. Downlink PT-RS may be transmitted on symbols to facilitate phase tracking at the receiver.

The UE may transmit an uplink DMRS to a base station for channel estimation. For example, the base station may use the uplink DMRS for coherent demodulation of one or more uplink physical channels. For example, the UE may transmit an uplink DMRS with a PUSCH and/or a PUCCH. The uplink DM-RS may span a range of frequencies that is similar to a range of frequencies associated with the corresponding physical channel. The base station may configure the UE with one or more uplink DMRS configurations. At least one DMRS configuration may support a front-loaded DMRS pattern. The front-loaded DMRS may be mapped over one or more OFDM symbols (e.g., one or two adjacent OFDM symbols). One or more uplink DMRSs may be configured to transmit at one or more symbols of a PUSCH and/or a PUCCH. The base station may semi-statically configure the UE with a number (e.g. maximum number) of front-loaded DMRS symbols for the PUSCH and/or the PUCCH, which the UE may use to schedule a single-symbol DMRS and/or a double-symbol DMRS. An NR network may support (e.g., for cyclic prefix orthogonal frequency division multiplexing (CP-OFDM)) a common DMRS structure for downlink and uplink, wherein a DMRS location, a DMRS pattern, and/or a scrambling sequence for the DMRS may be the same or different.

A PUSCH may comprise one or more layers, and the UE may transmit at least one symbol with DMRS present on a layer of the one or more layers of the PUSCH. In an example, a higher layer may configure up to three DMRSs for the PUSCH.

Uplink PT-RS (which may be used by a base station for phase tracking and/or phase-noise compensation) may or may not be present depending on an RRC configuration of the UE. The presence and/or pattern of uplink PT-RS may be configured on a UE-specific basis by a combination of RRC signaling and/or one or more parameters employed for other purposes (e.g., Modulation and Coding Scheme (MCS)), which may be indicated by DCI. When configured, a dynamic presence of uplink PT-RS may be associated with one or more DCI parameters comprising at least MCS. A radio network may support a plurality of uplink PT-RS densities defined in time/frequency domain. When present, a frequency domain density may be associated with at least one configuration of a scheduled bandwidth. The UE may assume a same precoding for a DMRS port and a PT-RS port. A number of PT-RS ports may be fewer than a number of DMRS ports in a scheduled resource. For example, uplink PT-RS may be confined in the scheduled time/frequency duration for the UE.

SRS may be transmitted by a UE to a base station for channel state estimation to support uplink channel dependent scheduling and/or link adaptation. SRS transmitted by the UE may allow a base station to estimate an uplink channel state at one or more frequencies. A scheduler at the base station may employ the estimated uplink channel state to assign one or more resource blocks for an uplink PUSCH transmission from the UE. The base station may semi-statically configure the UE with one or more SRS resource sets. For an SRS resource set, the base station may configure the UE with one or more SRS resources. An SRS resource set applicability may be configured by a higher layer (e.g., RRC) parameter. For example, when a higher layer parameter indicates beam management, an SRS resource in a SRS resource set of the one or more SRS resource sets (e.g., with the same/similar time domain behavior, periodic, aperiodic, and/or the like) may be transmitted at a time instant (e.g., simultaneously). The UE may transmit one or more SRS resources in SRS resource sets. An NR network may support aperiodic, periodic and/or semi-persistent SRS transmissions. The UE may transmit SRS resources based on one or more trigger types, wherein the one or more trigger types may comprise higher layer signaling (e.g., RRC) and/or one or more DCI formats. In an example, at least one DCI format may be employed for the UE to select at least one of one or more configured SRS resource sets. An SRS trigger type 0 may refer to an SRS triggered based on a higher layer signaling. An SRS trigger type 1 may refer to an SRS triggered based on one or more DCI formats. In an example, when PUSCH and SRS are transmitted in a same slot, the UE may be configured to transmit SRS after a transmission of a PUSCH and a corresponding uplink DMRS.

The base station may semi-statically configure the UE with one or more SRS configuration parameters indicating at least one of following: a SRS resource configuration identifier; a number of SRS ports; time domain behavior of an SRS resource configuration (e.g., an indication of periodic, semi-persistent, or aperiodic SRS); slot, mini-slot, and/or subframe level periodicity; offset for a periodic and/or an aperiodic SRS resource; a number of OFDM symbols in an SRS resource; a starting OFDM symbol of an SRS resource; an SRS bandwidth; a frequency hopping bandwidth; a cyclic shift; and/or an SRS sequence ID.

A network (e.g., a gNB and/or an ng-eNB of a network) and/or the UE may initiate a random access procedure. A UE in an RRC_IDLE state and/or an RRC_INACTIVE state may initiate the random access procedure to request a connection setup to a network. The UE may initiate the random access procedure from an RRC_CONNECTED state. The UE may initiate the random access procedure to request uplink resources (e.g., for uplink transmission of an SR when there is no PUCCH resource available) and/or acquire uplink timing (e.g., when uplink synchronization status is non-synchronized). The UE may initiate the random access procedure to request one or more system information blocks (SIBs) (e.g., other system information such as SIB2, SIB3, and/or the like). The UE may initiate the random access procedure for a beam failure recovery request. A network may initiate a random access procedure for a handover and/or for establishing time alignment for an SCell addition.

FIG. 17A illustrates a four-step contention-based random access procedure. Prior to initiation of the procedure, a base station may transmit a configuration message 1710 to the UE. The procedure illustrated in FIG. 17A comprises transmission of four messages: a Msg 1 1711, a Msg 2 1712, a Msg 3 1713, and a Msg 4 1714. The Msg 1 1711 may include and/or be referred to as a preamble (or a random access preamble). The Msg 2 1712 may include and/or be referred to as a random access response (RAR).

The configuration message 1710 may be transmitted, for example, using one or more RRC messages. The one or more RRC messages may indicate one or more random access channel (RACH) parameters to the UE. The one or more RACH parameters may comprise at least one of following: general parameters for one or more random access procedures (e.g., RACH-configGeneral); cell-specific parameters (e.g., RACH-ConfigCommon); and/or dedicated parameters (e.g., RACH-configDedicated). The base station may broadcast or multicast the one or more RRC messages to one or more UEs. The one or more RRC messages may be UE-specific (e.g., dedicated RRC messages transmitted to a UE in an RRC_CONNECTED state and/or in an RRC_INACTIVE state). The UE may determine, based on the one or more RACH parameters, a time-frequency resource and/or an uplink transmit power for transmission of the Msg 1 1711 and/or the Msg 3 1713. Based on the one or more RACH parameters, the UE may determine a reception timing and a downlink channel for receiving the Msg 2 1712 and the Msg 4 1714.

The one or more RACH parameters provided in the configuration message 1710 may indicate one or more Physical RACH (PRACH) occasions available for transmission of the Msg 1 1711. The one or more PRACH occasions may be predefined. The one or more RACH parameters may indicate one or more available sets of one or more PRACH occasions (e.g., prach-ConfigIndex). The one or more RACH parameters may indicate an association between (a) one or more PRACH occasions and (b) one or more reference signals. The one or more RACH parameters may indicate an association between (a) one or more preambles and (b) one or more reference signals. The one or more reference signals may be SS/PBCH blocks and/or CSI-RSs. For example, the one or more RACH parameters may indicate a number of SS/PBCH blocks mapped to a PRACH occasion and/or a number of preambles mapped to a SS/PBCH blocks.

The one or more RACH parameters provided in the configuration message 1710 may be used to determine an uplink transmit power of Msg 1 1711 and/or Msg 3 1713. For example, the one or more RACH parameters may indicate a reference power for a preamble transmission (e.g., a received target power and/or an initial power of the preamble transmission). There may be one or more power offsets indicated by the one or more RACH parameters. For example, the one or more RACH parameters may indicate: a power ramping step; a power offset between SSB and CSI-RS; a power offset between transmissions of the Msg 1 1711 and the Msg 3 1713; and/or a power offset value between preamble groups. The one or more RACH parameters may indicate one or more thresholds based on which the UE may determine at least one reference signal (e.g., an SSB and/or CSI-RS) and/or an uplink carrier (e.g., a normal uplink (NUL) carrier and/or a supplemental uplink (SUL) carrier).

The Msg 1 1711 may include one or more preamble transmissions (e.g., a preamble transmission and one or more preamble retransmissions). An RRC message may be used to configure one or more preamble groups (e.g., group A and/or group B). A preamble group may comprise one or more preambles. The UE may determine the preamble group based on a pathloss measurement and/or a size of the Msg 3 1713. The UE may measure an RSRP of one or more reference signals (e.g., SSBs and/or CSI-RSs) and determine at least one reference signal having an RSRP above an RSRP threshold (e.g., rsrp-ThresholdSSB and/or rsrp-ThresholdCSI-RS). The UE may select at least one preamble associated with the one or more reference signals and/or a selected preamble group, for example, if the association between the one or more preambles and the at least one reference signal is configured by an RRC message.

The UE may determine the preamble based on the one or more RACH parameters provided in the configuration message 1710. For example, the UE may determine the preamble based on a pathloss measurement, an RSRP measurement, and/or a size of the Msg 3 1713. As another example, the one or more RACH parameters may indicate: a preamble format; a maximum number of preamble transmissions; and/or one or more thresholds for determining one or more preamble groups (e.g., group A and group B). A base station may use the one or more RACH parameters to configure the UE with an association between one or more preambles and one or more reference signals (e.g., SSBs and/or CSI-RSs). If the association is configured, the UE may determine the preamble to include in Msg 1 1711 based on the association. The Msg 1 1711 may be transmitted to the base station via one or more PRACH occasions. The UE may use one or more reference signals (e.g., SSBs and/or CSI-RSs) for selection of the preamble and for determining of the PRACH occasion. One or more RACH parameters (e.g., ra-ssb-OccasionMskIndex and/or ra-OccasionList) may indicate an association between the PRACH occasions and the one or more reference signals.

The UE may perform a preamble retransmission if no response is received following a preamble transmission. The UE may increase an uplink transmit power for the preamble retransmission. The UE may select an initial preamble transmit power based on a pathloss measurement and/or a target received preamble power configured by the network. The UE may determine to retransmit a preamble and may ramp up the uplink transmit power. The UE may receive one or more RACH parameters (e.g., PREAMBLE_POWER_RAMPING_STEP) indicating a ramping step for the preamble retransmission. The ramping step may be an amount of incremental increase in uplink transmit power for a retransmission. The UE may ramp up the uplink transmit power if the UE determines a reference signal (e.g., SSB and/or CSI-RS) that is the same as a previous preamble transmission. The UE may count a number of preamble transmissions and/or retransmissions (e.g., PREAMBLE_TRANSMISSION_COUNTER). The UE may determine that a random access procedure completed unsuccessfully, for example, if the number of preamble transmissions exceeds a threshold configured by the one or more RACH parameters (e.g., preambleTransMax).

The Msg 2 1712 received by the UE may include an RAR. In some scenarios, the Msg 2 1712 may include multiple RARs corresponding to multiple UEs. The Msg 2 1712 may be received after or in response to the transmitting of the Msg 1 1711. The Msg 2 1712 may be scheduled on the DL-SCH and indicated on a PDCCH using a random access RNTI (RA-RNTI). The Msg 2 1712 may indicate that the Msg 1 1711 was received by the base station. The Msg 2 1712 may include a time-alignment command that may be used by the UE to adjust the UE's transmission timing, a scheduling grant for transmission of the Msg 3 1713, and/or a Temporary Cell RNTI (TC-RNTI). After transmitting a preamble, the UE may start a time window (e.g., ra-ResponseWindow) to monitor a PDCCH for the Msg 2 1712. The UE may determine when to start the time window based on a PRACH occasion that the UE uses to transmit the preamble. For example, the UE may start the time window one or more symbols after a last symbol of the preamble (e.g., at a first PDCCH occasion from an end of a preamble transmission). The one or more symbols may be determined based on a numerology. The PDCCH may be in a common search space (e.g., a Type1-PDCCH common search space) configured by an RRC message. The UE may identify the RAR based on a Radio Network Temporary Identifier (RNTI). RNTIs may be used depending on one or more events initiating the random access procedure. The UE may use random access RNTI (RA-RNTI). The RA-RNTI may be associated with PRACH occasions in which the UE transmits a preamble. For example, the UE may determine the RA-RNTI based on: an OFDM symbol index; a slot index; a frequency domain index; and/or a UL carrier indicator of the PRACH occasions. An example of RA-RNTI may be as follows: RA-RNTI=1+s_id+14×t_id+14×80×f_id+14×80×8×ul_carrier_id where s_id may be an index of a first OFDM symbol of the PRACH occasion (e.g., 0≤s_id<14), t_id may be an index of a first slot of the PRACH occasion in a system frame (e.g., 0≤t_id<80), fid may be an index of the PRACH occasion in the frequency domain (e.g., 0≤f_id<8), and ul_carrier_id may be a UL carrier used for a preamble transmission (e.g., 0 for an NUL carrier, and 1 for an SUL carrier).

The UE may transmit the Msg 3 1713 in response to a successful reception of the Msg 2 1712 (e.g., using resources identified in the Msg 2 1712). The Msg 3 1713 may be used for contention resolution in, for example, the contention-based random access procedure illustrated in FIG. 17A. In some scenarios, a plurality of UEs may transmit a same preamble to a base station and the base station may provide an RAR that corresponds to a UE. Collisions may occur if the plurality of UEs interpret the RAR as corresponding to themselves. Contention resolution (e.g., using the Msg 3 1713 and the Msg 4 1714) may be used to increase the likelihood that the UE does not incorrectly use an identity of another the UE. To perform contention resolution, the UE may include a device identifier in the Msg 3 1713 (e.g., a C-RNTI if assigned, a TC-RNTI included in the Msg 2 1712, and/or any other suitable identifier).

The Msg 4 1714 may be received after or in response to the transmitting of the Msg 3 1713. If a C-RNTI was included in the Msg 3 1713, the base station will address the UE on the PDCCH using the C-RNTI. If the UE's unique C-RNTI is detected on the PDCCH, the random access procedure is determined to be successfully completed. If a TC-RNTI is included in the Msg 3 1713 (e.g., if the UE is in an RRC_IDLE state or not otherwise connected to the base station), Msg 4 1714 will be received using a DL-SCH associated with the TC-RNTI. If a MAC PDU is successfully decoded and a MAC PDU comprises the UE contention resolution identity MAC CE that matches or otherwise corresponds with the CCCH SDU sent (e.g., transmitted) in Msg 3 1713, the UE may determine that the contention resolution is successful and/or the UE may determine that the random access procedure is successfully completed.

The UE may be configured with a supplementary uplink (SUL) carrier and a normal uplink (NUL) carrier. An initial access (e.g., random access procedure) may be supported in an uplink carrier. For example, a base station may configure the UE with two separate RACH configurations: one for an SUL carrier and the other for an NUL carrier. For random access in a cell configured with an SUL carrier, the network may indicate which carrier to use (NUL or SUL). The UE may determine the SUL carrier, for example, if a measured quality of one or more reference signals is lower than a broadcast threshold. Uplink transmissions of the random access procedure (e.g., the Msg 1 1711 and/or the Msg 3 1713) may remain on the selected carrier. The UE may switch an uplink carrier during the random access procedure (e.g., between the Msg 1 1711 and the Msg 3 1713) in one or more cases. For example, the UE may determine and/or switch an uplink carrier for the Msg 1 1711 and/or the Msg 3 1713 based on a channel clear assessment (e.g., a listen-before-talk).

FIG. 17B illustrates a two-step contention-free random access procedure. Similar to the four-step contention-based random access procedure illustrated in FIG. 17A, a base station may, prior to initiation of the procedure, transmit a configuration message 1720 to the UE. The configuration message 1720 may be analogous in some respects to the configuration message 1710. The procedure illustrated in FIG. 17B comprises transmission of two messages: a Msg 1 1721 and a Msg 2 1722. The Msg 1 1721 and the Msg 2 1722 may be analogous in some respects to the Msg 1 1711 and a Msg 2 1712 illustrated in FIG. 17A, respectively. As will be understood from FIGS. 17A and 17B, the contention-free random access procedure may not include messages analogous to the Msg 3 1713 and/or the Msg 4 1714.

The contention-free random access procedure illustrated in FIG. 17B may be initiated for a beam failure recovery, other SI request, SCell addition, and/or handover. For example, a base station may indicate or assign to the UE the preamble to be used for the Msg 1 1721. The UE may receive, from the base station via PDCCH and/or RRC, an indication of a preamble (e.g., ra-PreambleIndex).

After transmitting a preamble, the UE may start a time window (e.g., ra-ResponseWindow) to monitor a PDCCH for the RAR. In the event of a beam failure recovery request, the base station may configure the UE with a separate time window and/or a separate PDCCH in a search space indicated by an RRC message (e.g., recoverySearchSpaceId). The UE may monitor for a PDCCH transmission addressed to a Cell RNTI (C-RNTI) on the search space. In the contention-free random access procedure illustrated in FIG. 17B, the UE may determine that a random access procedure successfully completes after or in response to transmission of Msg 1 1721 and reception of a corresponding Msg 2 1722. The UE may determine that a random access procedure successfully completes, for example, if a PDCCH transmission is addressed to a C-RNTI. The UE may determine that a random access procedure successfully completes, for example, if the UE receives an RAR comprising a preamble identifier corresponding to a preamble transmitted by the UE and/or the RAR comprises a MAC sub-PDU with the preamble identifier. The UE may determine the response as an indication of an acknowledgement for an SI request.

FIG. 17C illustrates another two-step random access procedure. Similar to the random access procedures illustrated in FIGS. 17A and 17B, a base station may, prior to initiation of the procedure, transmit a configuration message 1730 to the UE. The configuration message 1730 may be analogous in some respects to the configuration message 1710 and/or the configuration message 1720. The procedure illustrated in FIG. 17C comprises transmission of two messages: a Msg A 1731 and a Msg B 1732.

Msg A 1720 may be transmitted in an uplink transmission by the UE. Msg A 1720 may comprise one or more transmissions of a preamble 1741 and/or one or more transmissions of a transport block 1742. The transport block 1742 may comprise contents that are similar and/or equivalent to the contents of the Msg 3 1713 illustrated in FIG. 17A. The transport block 1742 may comprise UCI (e.g., an SR, a HARQ ACK/NACK, and/or the like). The UE may receive the Msg B 1750 after or in response to transmitting the Msg A 1720. The Msg B 1750 may comprise contents that are similar and/or equivalent to the contents of the Msg 2 1712 (e.g., an RAR) illustrated in FIGS. 17A and 17B and/or the Msg 4 1714 illustrated in FIG. 17A.

The UE may initiate the two-step random access procedure in FIG. 17C for licensed spectrum and/or unlicensed spectrum. The UE may determine, based on one or more factors, whether to initiate the two-step random access procedure. The one or more factors may be: a radio access technology in use (e.g., LTE, NR, and/or the like); whether the UE has valid TA or not; a cell size; the UE's RRC state; a type of spectrum (e.g., licensed vs. unlicensed); and/or any other suitable factors.

The UE may determine, based on two-step RACH parameters included in the configuration message 1730, a radio resource and/or an uplink transmit power for the preamble 1741 and/or the transport block 1742 included in the Msg A 1731. The RACH parameters may indicate a modulation and coding schemes (MCS), a time-frequency resource, and/or a power control for the preamble 1741 and/or the transport block 1742. A time-frequency resource for transmission of the preamble 1741 (e.g., a PRACH) and a time-frequency resource for transmission of the transport block 1742 (e.g., a PUSCH) may be multiplexed using FDM, TDM, and/or CDM. The RACH parameters may enable the UE to determine a reception timing and a downlink channel for monitoring for and/or receiving Msg B 1750.

The transport block 1742 may comprise data (e.g., delay-sensitive data), an identifier of the UE, security information, and/or device information (e.g., an International Mobile Subscriber Identity (IMSI)). The base station may transmit the Msg B 1732 as a response to the Msg A 1731. The Msg B 1732 may comprise at least one of following: a preamble identifier; a timing advance command; a power control command; an uplink grant (e.g., a radio resource assignment and/or an MCS); a UE identifier for contention resolution; and/or an RNTI (e.g., a C-RNTI or a TC-RNTI). The UE may determine that the two-step random access procedure is successfully completed if: a preamble identifier in the Msg B 1732 is matched to a preamble transmitted by the UE; and/or the identifier of the UE in Msg B 1732 is matched to the identifier of the UE in the Msg A 1731 (e.g., the transport block 1742).

A UE and a base station may exchange control signaling. The control signaling may be referred to as L1/L2 control signaling and may originate from the PHY layer (e.g., layer 1) and/or the MAC layer (e.g., layer 2). The control signaling may comprise downlink control signaling transmitted from the base station to the UE and/or uplink control signaling transmitted from the UE to the base station.

The downlink control signaling may comprise: a downlink scheduling assignment; an uplink scheduling grant indicating uplink radio resources and/or a transport format; a slot format information; a preemption indication; a power control command; and/or any other suitable signaling. The UE may receive the downlink control signaling in a payload transmitted by the base station on a physical downlink control channel (PDCCH). The payload transmitted on the PDCCH may be referred to as downlink control information (DCI). In some scenarios, the PDCCH may be a group common PDCCH (GC-PDCCH) that is common to a group of UEs.

A base station may attach one or more cyclic redundancy check (CRC) parity bits to a DCI in order to facilitate detection of transmission errors. When the DCI is intended for a UE (or a group of the UEs), the base station may scramble the CRC parity bits with an identifier of the UE (or an identifier of the group of the UEs). Scrambling the CRC parity bits with the identifier may comprise Modulo-2 addition (or an exclusive OR operation) of the identifier value and the CRC parity bits. The identifier may comprise a 16-bit value of a radio network temporary identifier (RNTI).

DCIs may be used for different purposes. A purpose may be indicated by the type of RNTI used to scramble the CRC parity bits. For example, a DCI having CRC parity bits scrambled with a paging RNTI (P-RNTI) may indicate paging information and/or a system information change notification. The P-RNTI may be predefined as “FFFE” in hexadecimal. A DCI having CRC parity bits scrambled with a system information RNTI (SI-RNTI) may indicate a broadcast transmission of the system information. The SI-RNTI may be predefined as “FFFF” in hexadecimal. A DCI having CRC parity bits scrambled with a random access RNTI (RA-RNTI) may indicate a random access response (RAR). A DCI having CRC parity bits scrambled with a cell RNTI (C-RNTI) may indicate a dynamically scheduled unicast transmission and/or a triggering of PDCCH-ordered random access. A DCI having CRC parity bits scrambled with a temporary cell RNTI (TC-RNTI) may indicate a contention resolution (e.g., a Msg 3 analogous to the Msg 3 1713 illustrated in FIG. 17A). Other RNTIs configured to the UE by a base station may comprise a Configured Scheduling RNTI (CS-RNTI), a Transmit Power Control-PUCCH RNTI (TPC-PUCCH-RNTI), a Transmit Power Control-PUSCH RNTI (TPC-PUSCH-RNTI), a Transmit Power Control-SRS RNTI (TPC-SRS-RNTI), an Interruption RNTI (INT-RNTI), a Slot Format Indication RNTI (SFI-RNTI), a Semi-Persistent CSI RNTI (SP-CSI-RNTI), a Modulation and Coding Scheme Cell RNTI (MCS-C-RNTI), and/or the like.

Depending on the purpose and/or content of a DCI, the base station may transmit the DCIs with one or more DCI formats. For example, DCI format 0_0 may be used for scheduling of PUSCH in a cell. DCI format 0_0 may be a fallback DCI format (e.g., with compact DCI payloads). DCI format 0_1 may be used for scheduling of PUSCH in a cell (e.g., with more DCI payloads than DCI format 0_0). DCI format 1_0 may be used for scheduling of PDSCH in a cell. DCI format 1_0 may be a fallback DCI format (e.g., with compact DCI payloads). DCI format 1_1 may be used for scheduling of PDSCH in a cell (e.g., with more DCI payloads than DCI format 1_0). DCI format 2_0 may be used for providing a slot format indication to a group of UEs. DCI format 2_1 may be used for notifying a group of UEs of a physical resource block and/or OFDM symbol where the UE may assume no transmission is intended to the UE. DCI format 2_2 may be used for transmission of a transmit power control (TPC) command for PUCCH or PUSCH. DCI format 2_3 may be used for transmission of a group of TPC commands for SRS transmissions by one or more UEs. DCI format(s) for new functions may be defined in future releases. DCI formats may have different DCI sizes, or may share the same DCI size.

After scrambling a DCI with a RNTI, the base station may process the DCI with channel coding (e.g., polar coding), rate matching, scrambling and/or QPSK modulation. A base station may map the coded and modulated DCI on resource elements used and/or configured for a PDCCH. Based on a payload size of the DCI and/or a coverage of the base station, the base station may transmit the DCI via a PDCCH occupying a number of contiguous control channel elements (CCEs). The number of the contiguous CCEs (referred to as aggregation level) may be 1, 2, 4, 8, 16, and/or any other suitable number. A CCE may comprise a number (e.g., 6) of resource-element groups (REGs). A REG may comprise a resource block in an OFDM symbol. The mapping of the coded and modulated DCI on the resource elements may be based on mapping of CCEs and REGs (e.g., CCE-to-REG mapping).

FIG. 18A illustrates an example of CORESET configurations for a bandwidth part. The base station may transmit a DCI via a PDCCH on one or more control resource sets (CORESETs). A CORESET may comprise a time-frequency resource in which the UE tries to decode a DCI using one or more search spaces. The base station may configure a size and a location of the CORESET in the time-frequency domain. In the example of FIG. 18A, a first CORESET 1801 and a second CORESET 1802 occur at the first symbol in a slot. The first CORESET 1801 overlaps with the second CORESET 1802 in the frequency domain. A third CORESET 1803 occurs at a third symbol in the slot. A fourth CORESET 1804 occurs at the seventh symbol in the slot. CORESETs may have a different number of resource blocks in frequency domain.

FIG. 18B illustrates an example of a CCE-to-REG mapping for DCI transmission on a CORESET and PDCCH processing. The CCE-to-REG mapping may be an interleaved mapping (e.g., for the purpose of providing frequency diversity) or a non-interleaved mapping (e.g., for the purposes of facilitating interference coordination and/or frequency-selective transmission of control channels). The base station may perform different or same CCE-to-REG mapping on different CORESETs. A CORESET may be associated with a CCE-to-REG mapping by RRC configuration. A CORESET may be configured with an antenna port quasi co-location (QCL) parameter. The antenna port QCL parameter may indicate QCL information of a demodulation reference signal (DMRS) for PDCCH reception in the CORESET.

The base station may transmit, to the UE, RRC messages comprising configuration parameters of one or more CORESETs and one or more search space sets. The configuration parameters may indicate an association between a search space set and a CORESET. A search space set may comprise a set of PDCCH candidates formed by CCEs at a given aggregation level. The configuration parameters may indicate: a number of PDCCH candidates to be monitored per aggregation level; a PDCCH monitoring periodicity and a PDCCH monitoring pattern; one or more DCI formats to be monitored by the UE; and/or whether a search space set is a common search space set or a UE-specific search space set. A set of CCEs in the common search space set may be predefined and known to the UE. A set of CCEs in the UE-specific search space set may be configured based on the UE's identity (e.g., C-RNTI).

As shown in FIG. 18B, the UE may determine a time-frequency resource for a CORESET based on RRC messages. The UE may determine a CCE-to-REG mapping (e.g., interleaved or non-interleaved, and/or mapping parameters) for the CORESET based on configuration parameters of the CORESET. The UE may determine a number (e.g., at most 10) of search space sets configured on the CORESET based on the RRC messages. The UE may monitor a set of PDCCH candidates according to configuration parameters of a search space set. The UE may monitor a set of PDCCH candidates in one or more CORESETs for detecting one or more DCIs. Monitoring may comprise decoding one or more PDCCH candidates of the set of the PDCCH candidates according to the monitored DCI formats. Monitoring may comprise decoding a DCI content of one or more PDCCH candidates with possible (or configured) PDCCH locations, possible (or configured) PDCCH formats (e.g., number of CCEs, number of PDCCH candidates in common search spaces, and/or number of PDCCH candidates in the UE-specific search spaces) and possible (or configured) DCI formats. The decoding may be referred to as blind decoding. The UE may determine a DCI as valid for the UE, in response to CRC checking (e.g., scrambled bits for CRC parity bits of the DCI matching a RNTI value). The UE may process information contained in the DCI (e.g., a scheduling assignment, an uplink grant, power control, a slot format indication, a downlink preemption, and/or the like).

The UE may transmit uplink control signaling (e.g., uplink control information (UCI)) to a base station. The uplink control signaling may comprise hybrid automatic repeat request (HARQ) acknowledgements for received DL-SCH transport blocks. The UE may transmit the HARQ acknowledgements after receiving a DL-SCH transport block. Uplink control signaling may comprise channel state information (CSI) indicating channel quality of a physical downlink channel. The UE may transmit the CSI to the base station. The base station, based on the received CSI, may determine transmission format parameters (e.g., comprising multi-antenna and beamforming schemes) for a downlink transmission. Uplink control signaling may comprise scheduling requests (SR). The UE may transmit an SR indicating that uplink data is available for transmission to the base station. The UE may transmit a UCI (e.g., HARQ acknowledgements (HARQ-ACK), CSI report, SR, and the like) via a physical uplink control channel (PUCCH) or a physical uplink shared channel (PUSCH). The UE may transmit the uplink control signaling via a PUCCH using one of several PUCCH formats.

There may be five PUCCH formats and the UE may determine a PUCCH format based on a size of the UCI (e.g., a number of uplink symbols of UCI transmission and a number of UCI bits). PUCCH format 0 may have a length of one or two OFDM symbols and may include two or fewer bits. The UE may transmit UCI in a PUCCH resource using PUCCH format 0 if the transmission is over one or two symbols and the number of HARQ-ACK information bits with positive or negative SR (HARQ-ACK/SR bits) is one or two. PUCCH format 1 may occupy a number between four and fourteen OFDM symbols and may include two or fewer bits. The UE may use PUCCH format 1 if the transmission is four or more symbols and the number of HARQ-ACK/SR bits is one or two. PUCCH format 2 may occupy one or two OFDM symbols and may include more than two bits. The UE may use PUCCH format 2 if the transmission is over one or two symbols and the number of UCI bits is two or more. PUCCH format 3 may occupy a number between four and fourteen OFDM symbols and may include more than two bits. The UE may use PUCCH format 3 if the transmission is four or more symbols, the number of UCI bits is two or more and PUCCH resource does not include an orthogonal cover code. PUCCH format 4 may occupy a number between four and fourteen OFDM symbols and may include more than two bits. The UE may use PUCCH format 4 if the transmission is four or more symbols, the number of UCI bits is two or more and the PUCCH resource includes an orthogonal cover code.

The base station may transmit configuration parameters to the UE for a plurality of PUCCH resource sets using, for example, an RRC message. The plurality of PUCCH resource sets (e.g., up to four sets) may be configured on an uplink BWP of a cell. A PUCCH resource set may be configured with a PUCCH resource set index, a plurality of PUCCH resources with a PUCCH resource being identified by a PUCCH resource identifier (e.g., pucch-Resourceid), and/or a number (e.g. a maximum number) of UCI information bits the UE may transmit using one of the plurality of PUCCH resources in the PUCCH resource set. When configured with a plurality of PUCCH resource sets, the UE may select one of the plurality of PUCCH resource sets based on a total bit length of the UCI information bits (e.g., HARQ-ACK, SR, and/or CSI). If the total bit length of UCI information bits is two or fewer, the UE may select a first PUCCH resource set having a PUCCH resource set index equal to “0”. If the total bit length of UCI information bits is greater than two and less than or equal to a first configured value, the UE may select a second PUCCH resource set having a PUCCH resource set index equal to “1”. If the total bit length of UCI information bits is greater than the first configured value and less than or equal to a second configured value, the UE may select a third PUCCH resource set having a PUCCH resource set index equal to “2”. If the total bit length of UCI information bits is greater than the second configured value and less than or equal to a third value (e.g., 1706), the UE may select a fourth PUCCH resource set having a PUCCH resource set index equal to “3”.

After determining a PUCCH resource set from a plurality of PUCCH resource sets, the UE may determine a PUCCH resource from the PUCCH resource set for UCI (HARQ-ACK, CSI, and/or SR) transmission. The UE may determine the PUCCH resource based on a PUCCH resource indicator in a DCI (e.g., with a DCI format 1_0 or DCI for 1_1) received on a PDCCH. A three-bit PUCCH resource indicator in the DCI may indicate one of eight PUCCH resources in the PUCCH resource set. Based on the PUCCH resource indicator, the UE may transmit the UCI (HARQ-ACK, CSI and/or SR) using a PUCCH resource indicated by the PUCCH resource indicator in the DCI.

FIG. 19 illustrates an example of a wireless device 1902 in communication with a base station 1904 in accordance with embodiments of the present disclosure. The wireless device 1902 and base station 1904 may be part of a mobile communication network, such as the mobile communication network 100 illustrated in FIG. 1A, the mobile communication network 150 illustrated in FIG. 1B, or any other communication network. Only one wireless device 1902 and one base station 1904 are illustrated in FIG. 19 , but it will be understood that a mobile communication network may include more than one UE and/or more than one base station, with the same or similar configuration as those shown in FIG. 19 .

The base station 1904 may connect the wireless device 1902 to a core network (not shown) through radio communications over the air interface (or radio interface) 1906. The communication direction from the base station 1904 to the wireless device 1902 over the air interface 1906 is known as the downlink, and the communication direction from the wireless device 1902 to the base station 1904 over the air interface is known as the uplink. Downlink transmissions may be separated from uplink transmissions using FDD, TDD, and/or some combination of the two duplexing techniques.

In the downlink, data to be sent to the wireless device 1902 from the base station 1904 may be provided to the processing system 1908 of the base station 1904. The data may be provided to the processing system 1908 by, for example, a core network. In the uplink, data to be sent to the base station 1904 from the wireless device 1902 may be provided to the processing system 1918 of the wireless device 1902. The processing system 1908 and the processing system 1918 may implement layer 3 and layer 2 OSI functionality to process the data for transmission. Layer 2 may include an SDAP layer, a PDCP layer, an RLC layer, and a MAC layer, for example, with respect to FIG. 2A, FIG. 2B, FIG. 3 , and FIG. 4A. Layer 3 may include an RRC layer as with respect to FIG. 2B.

After being processed by processing system 1908, the data to be sent to the wireless device 1902 may be provided to a transmission processing system 1910 of base station 1904. Similarly, after being processed by the processing system 1918, the data to be sent to base station 1904 may be provided to a transmission processing system 1920 of the wireless device 1902. The transmission processing system 1910 and the transmission processing system 1920 may implement layer 1 OSI functionality. Layer 1 may include a PHY layer with respect to FIG. 2A, FIG. 2B, FIG. 3 , and FIG. 4A. For transmit processing, the PHY layer may perform, for example, forward error correction coding of transport channels, interleaving, rate matching, mapping of transport channels to physical channels, modulation of physical channel, multiple-input multiple-output (MIMO) or multi-antenna processing, and/or the like.

At the base station 1904, a reception processing system 1912 may receive the uplink transmission from the wireless device 1902. At the wireless device 1902, a reception processing system 1922 may receive the downlink transmission from base station 1904. The reception processing system 1912 and the reception processing system 1922 may implement layer 1 OSI functionality. Layer 1 may include a PHY layer with respect to FIG. 2A, FIG. 2B, FIG. 3 , and FIG. 4A. For receive processing, the PHY layer may perform, for example, error detection, forward error correction decoding, deinterleaving, demapping of transport channels to physical channels, demodulation of physical channels, MIMO or multi-antenna processing, and/or the like.

As shown in FIG. 19 , a wireless device 1902 and the base station 1904 may include multiple antennas. With respect to FIG. 12 , the multiple antennas may be used to perform one or more MIMO or multi-antenna techniques, such as spatial multiplexing (e.g., single-user MIMO or multi-user MIMO), transmit/receive diversity, and/or beamforming. In other examples, the wireless device 1902 and/or the base station 1904 may have a single antenna.

The processing system 1908 and the processing system 1918 may be associated with a memory 1914 and a memory 1924, respectively. Memory 1914 and memory 1924 (e.g., one or more non-transitory computer readable mediums) may store computer program instructions or code that may be executed by the processing system 1908 and/or the processing system 1918 to carry out one or more of the functionalities discussed in the present application. Although not shown in FIG. 19 , the transmission processing system 1910, the transmission processing system 1920, the reception processing system 1912, and/or the reception processing system 1922 may be coupled to a memory (e.g., one or more non-transitory computer readable mediums) storing computer program instructions or code that may be executed to carry out one or more of their respective functionalities.

The processing system 1908 and/or the processing system 1918 may comprise one or more controllers and/or one or more processors. The one or more controllers and/or one or more processors may comprise, for example, a general-purpose processor, a digital signal processor (DSP), a microcontroller, an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) and/or other programmable logic device, discrete gate and/or transistor logic, discrete hardware components, an on-board unit, or any combination thereof. The processing system 1908 and/or the processing system 1918 may perform at least one of signal coding/processing, data processing, power control, input/output processing, and/or any other functionality that may enable the wireless device 1902 and the base station 1904 to operate in a wireless environment.

The processing system 1908 and/or the processing system 1918 may be connected to one or more peripherals 1916 and one or more peripherals 1926, respectively. The one or more peripherals 1916 and the one or more peripherals 1926 may include software and/or hardware that provide features and/or functionalities, for example, a speaker, a microphone, a keypad, a display, a touchpad, a power source, a satellite transceiver, a universal serial bus (USB) port, a hands-free headset, a frequency modulated (FM) radio unit, a media player, an Internet browser, an electronic control unit (e.g., for a motor vehicle), and/or one or more sensors (e.g., an accelerometer, a gyroscope, a temperature sensor, a radar sensor, a lidar sensor, an ultrasonic sensor, a light sensor, a camera, and/or the like). The processing system 1908 and/or the processing system 1918 may receive user input data from and/or provide user output data to the one or more peripherals 1916 and/or the one or more peripherals 1926. The processing system 1918 in the wireless device 1902 may receive power from a power source and/or may be configured to distribute the power to the other components in the wireless device 1902. The power source may comprise one or more sources of power, for example, a battery, a solar cell, a fuel cell, or any combination thereof. The processing system 1908 and/or the processing system 1918 may be connected to a GPS chipset 1917 and a GPS chipset 1927, respectively. The GPS chipset 1917 and the GPS chipset 1927 may be configured to provide geographic location information of the wireless device 1902 and the base station 1904, respectively.

FIG. 20A illustrates an example structure for uplink transmission. A baseband signal representing a physical uplink shared channel may perform one or more functions. The one or more functions may comprise at least one of: scrambling; modulation of scrambled bits to generate complex-valued symbols; mapping of the complex-valued modulation symbols onto one or several transmission layers; transform precoding to generate complex-valued symbols; precoding of the complex-valued symbols; mapping of precoded complex-valued symbols to resource elements; generation of complex-valued time-domain Single Carrier-Frequency Division Multiple Access (SC-FDMA) or CP-OFDM signal for an antenna port; and/or the like. In an example, when transform precoding is enabled, a SC-FDMA signal for uplink transmission may be generated. In an example, when transform precoding is not enabled, an CP-OFDM signal for uplink transmission may be generated by FIG. 20A. These functions are illustrated as examples and it is anticipated that other mechanisms may be implemented in various embodiments.

FIG. 20B illustrates an example structure for modulation and up-conversion of a baseband signal to a carrier frequency. The baseband signal may be a complex-valued SC-FDMA or CP-OFDM baseband signal for an antenna port and/or a complex-valued Physical Random Access Channel (PRACH) baseband signal. Filtering may be employed prior to transmission.

FIG. 20C illustrates an example structure for downlink transmissions. A baseband signal representing a physical downlink channel may perform one or more functions. The one or more functions may comprise: scrambling of coded bits in a codeword to be transmitted on a physical channel; modulation of scrambled bits to generate complex-valued modulation symbols; mapping of the complex-valued modulation symbols onto one or several transmission layers; precoding of the complex-valued modulation symbols on a layer for transmission on the antenna ports; mapping of complex-valued modulation symbols for an antenna port to resource elements; generation of complex-valued time-domain OFDM signal for an antenna port; and/or the like. These functions are illustrated as examples and it is anticipated that other mechanisms may be implemented in various embodiments.

FIG. 20D illustrates another example structure for modulation and up-conversion of a baseband signal to a carrier frequency. The baseband signal may be a complex-valued OFDM baseband signal for an antenna port. Filtering may be employed prior to transmission.

A wireless device may receive from a base station one or more messages (e.g. RRC messages) comprising configuration parameters of a plurality of cells (e.g. primary cell, secondary cell). The wireless device may communicate with at least one base station (e.g. two or more base stations in dual-connectivity) via the plurality of cells. The one or more messages (e.g. as a part of the configuration parameters) may comprise parameters of physical, MAC, RLC, PCDP, SDAP, RRC layers for configuring the wireless device. For example, the configuration parameters may comprise parameters for configuring physical and MAC layer channels, bearers, etc. For example, the configuration parameters may comprise parameters indicating values of timers for physical, MAC, RLC, PCDP, SDAP, RRC layers, and/or communication channels.

A timer may be running once it is started, until it is stopped or until it expires; otherwise it is not running. A timer may be started if it is not running or restarted if it is running. A timer may be associated with a value (e.g. may be started or restarted from a value, or may be started from zero or reach the value. Other equal example implementation may be provided). The duration of a timer may not be updated until they are stopped or expires (e.g. due to BWP switching). A timer may be used to measure a time period/window for a process. When the specification refers to implementation and procedures related to one or more timers, it is understood that there are multiple ways to implement the one or more timers. The multiple ways to implement a timer may measure a time period/window for a process. For example, a random access response window timer may be used for measuring a window of time for receiving a random access response. In an example, instead of starting and expiry of a random access response window timer, the time difference between two time stamps may be used. When a timer is restarted, a process for measurement of time window may be restarted. Other example implementations may be provided to restart a measurement of a time window.

In an example, wireless devices may communicate via a sidelink, which may be a direct interface (e.g., PC5 interface) configured between wireless devices. A communication of wireless devices via a sidelink may employ a resource pool that may be informed by a base station. In an implementation of existing technologies, if a wireless device using sidelink communication performs a handover to a target cell that is congested with sidelink traffic, the wireless device may experience service quality decrease and/or service interruption at the target cell. In an example, when a wireless device performs a handover to a target cell using an unlicensed spectrum that is in a high traffic load status, the wireless device may experience decrease of service quality and/or service interruption at the target cell.

Embodiments of the present disclosure may provide enhanced signaling mechanisms for wireless network nodes that support sidelink communications and/or use an unlicensed spectrum. Enhanced signaling mechanisms among network nodes may provide reliable services for wireless devices. In an example embodiment, a base station may provide, to its neighboring base station, channel congestion information of a resource pool for a sidelink. The neighboring base station that receives the channel congestion information may determine a handover initiation and/or a secondary node addition/modification (e.g., SCG configuration) for a wireless device that may employ sidelink communication. In an example embodiment, a base station may provide, to its neighboring base station, channel congestion information of a cell using an unlicensed spectrum. The neighboring base station that receives the channel congestion information may determine a handover initiation and/or a secondary node addition/modification (e.g., SCG configuration) for a wireless device to be configured with the cell using the unlicensed spectrum. The channel congestion information may comprise a received signal strength indicator (RSSI), a channel busy ratio (CBR), a channel occupancy ratio (CR), and/or the like. Example embodiments may increase communication reliability and decrease service latency.

In an example, D2D (device to device) communication literally means communication between an electronic device and an electronic device. According to a D2D communication scheme or a UE-to-UE communication scheme, data may be exchanged between UEs without passing through a base station. A link directly established between devices may be referred to as a D2D link or a sidelink. The D2D communication may have merits in that latency is reduced compared to a legacy base station-centered communication scheme and a less radio resource is required, and the like. In this case, although a UE corresponds to a terminal of a user, if such a network device as an eNB or a gNB transmits and receives a signal according to a communication scheme between UEs, the network device may be considered as a sort of UEs.

FIG. 21 shows deployment examples of types of UE performing D2D communication and cell coverage. Referring to FIG. 21A, types of UE A and B may be placed outside cell coverage. Referring to FIG. 21B, UE A may be placed within cell coverage, and UE B may be placed outside cell coverage. Referring to FIG. 21C, types of UE A and B may be placed within single cell coverage. Referring to FIG. 21D, UE A may be placed within coverage of a first cell, and UE B may be placed within coverage of a second cell.

In an example, a D2D transmission signal transmitted through a sidelink may be divided into a discovery use and a communication use. A discovery signal corresponds to a signal used by a UE to determine a plurality of UEs adjacent to the UE. As an example of a sidelink channel for transmitting and receiving the discovery signal, there is a sidelink discovery channel (PSDCH: Physical Sidelink Discovery Channel). A communication signal corresponds to a signal for transmitting general data (e.g., voice, image, video, safety information, etc.) to be transmitted by a UE. As an example of a sidelink channel for transmitting and receiving the communication signal, there are a physical sidelink broadcast channel (PSBCH), a physical sidelink shared channel (PSSCH), a physical sidelink control channel (PSCCH), and the like.

FIG. 22 shows an example of a UE A, a UE B and a radio resources used by the UE A and the UE B performing D2D communication. In FIG. 22A, a UE corresponds to a terminal or such a network device as a base station transmitting and receiving a signal according to a D2D communication scheme. A UE selects a resource unit corresponding to a specific resource from a resource pool corresponding to a set of resources and the UE transmits a D2D signal using the selected resource unit. The UE B corresponding to a reception UE receives a configuration of a resource pool in which the UE A is able to transmit a signal and the UE B is able to detect a signal of the UE A in the resource pool. In this case, if the UE A is located at the inside of network coverage of a base station, the base station may inform the UE A of the resource pool. If the UE A is located at the outside of network coverage of the base station, the resource pool may be informed by a different UE or may be determined by a preconfigured resource pool. In general, a resource pool includes a plurality of resource units. One resource unit may be comprised of a group of resource blocks. A UE selects one or more resource units from a plurality of the resource units and may be able to use the selected resource unit(s) for D2D signal transmission. FIG. 22B shows an example of configuring a resource unit. Referring to FIG. 22B, the entire frequency resources are divided into the Nf number of resource units per a unit time resource (e.g. slot or a group of slots). A resource pool may be repeated with a period of k unit time resources and a resource pool may be configured within a bandwidth part for D2D or sidelink communication. Specifically, as shown in FIG. 22 , one resource unit may periodically and repeatedly appear, or, an index of a physical resource unit to which a logical resource unit is mapped may change with a predetermined pattern according to time to obtain a diversity gain in time domain and/or frequency domain. In this resource unit structure, a resource pool may correspond to a set of resource units capable of being used by a UE intending to transmit or receive a D2D signal.

In an example, a resource pool may be classified into various types. A resource pool may be classified according to contents of a D2D signal transmitted via each resource pool. For example, the contents of the D2D signal may be classified into various signals and a separate resource pool may be configured according to each of the contents. The contents of the D2D signal may include a D2D control channel, a D2D data channel, and/or a discovery channel. The D2D control channel may correspond to a signal including information on a resource position of a D2D data channel, information on MCS necessary for modulating and demodulating a data channel, information on a MIMO transmission scheme, information on packet priority, information on target coverage, information on QoS requirement or the like. The D2D control channel may be transmitted on an identical resource unit in a manner of being multiplexed with D2D data channel. In this case, a D2D control and data channel resource pool may correspond to a pool of resources that D2D control and D2D data are transmitted in a manner of being multiplexed. As shown in FIG. 26 , the D2D control channel may also be referred to as a PSCCH (physical sidelink control channel). The D2D data channel (or, PSSCH (physical sidelink shared channel)) corresponds to a resource pool used by a transmission UE to transmit user data. If a D2D control and a D2D data are transmitted in a manner of being multiplexed in an identical resource unit, D2D data channel except D2D control information may be transmitted only in a resource pool for the D2D data channel. In other word, resource elements (REs), which are used to transmit D2D control information in a specific resource unit of a D2D control resource pool, may also be used for transmitting D2D data in a D2D data channel resource pool. The discovery channel may correspond to a resource pool for a message that enables a neighboring UE to discover transmission UE transmitting information such as ID of the UE, and the like.

In an example, a resource pool may be classified to support different QoS level or different service. For example, the priority level for each resource pool may be configured by a base station, or the service to be supported for each resource pool may be configured differently. Alternatively, a specific resource pool may be configured to use only a specific unicast or groupcast UEs. Although contents of D2D signal are identical to each other, it may use a different resource pool according to a transmission/reception attribute of the D2D signal. For example, in case of the same D2D data channel or the same discovery message, the D2D data channel or the discovery signal may be classified into a different resource pool according to a transmission timing determination scheme (e.g., whether a D2D signal is transmitted at the time of receiving a synchronization reference signal or the timing to which a prescribed timing advance is added) of a D2D signal, a resource allocation scheme (e.g., whether a transmission resource of an individual signal is designated by a base station or an individual transmission UE selects an individual signal transmission resource from a pool), a signal format (e.g., number of symbols occupied by a D2D signal in a subframe, number of subframes used for transmitting a D2D signal), signal strength from a base station, strength of transmit power of a D2D UE, and the like. For clarity, a method for a base station to directly designate a transmission resource of a D2D transmission UE is referred to as a Mode 1. In Mode 1, a base station such as eNB or gNB may transmit DCI to schedule D2D signal transmission. If a transmission resource region (or resource pool) is (pre)configured or a base station designates the transmission resource region or resource pool and a UE directly selects a transmission resource from the transmission resource region (or resource pool), it is referred to as a Mode 2. In case of performing D2D discovery, if a base station directly indicates a transmission resource, it is referred to as a Type 2. If a UE directly selects a transmission resource from a predetermined resource pool or a resource pool indicated by the base station, it is referred to as a Type 1.

In an example, for D2D communication, it may be necessary to obtain time synchronization and frequency synchronization between two UEs. If the two UEs belong to the coverage of a cell, the two UEs may be synchronized by a PSS/SSS, or the like transmitted by the base station and the time/frequency synchronization may be maintained between the two UEs in a level that the two UEs are able to directly transmit and receive a signal. Alternatively, a UE may transmit synchronization signal and another UE may be synchronized to the synchronization signal transmitted by the UE. This synchronization signal transmitted by a UE may be referred to as a sidelink synchronization signal (SLSS). SLSS may comprise sidelink primary synchronization signal (S-PSS) and sidelink secondary synchronization signal (S-SSS). SLSS may be transmitted with physical sidelink broadcast channel (PSBCH) to convey some basic or initial system information. Additionally, a UE may synchronize or derive a timing of transmission time intervals (e.g., frames, subframes, slots, and/or the like) using global navigation satellite system (GNSS) timing. S-PSS, S-SSS and PSBCH may be structured in a block format (sidelink synchronization signal block (S-SSB)) which may support periodic transmission. The S-SSB may have the same numerology (i.e. SCS and CP length) as sidelink data channel and sidelink control channel in a carrier, transmission bandwidth may be within the (pre-) configured sidelink BWP, and its frequency location may be (pre-)configured, as shown in FIG. 27 and/or FIG. 28 . This may lead to no need for the UE to perform hypothesis detection in frequency to find S-SSB in a carrier. Sidelink synchronization sources may be GNSS, gNB, eNB, or NR UE. Each sidelink synchronization source may be associated with a synchronization priority level in which the priority order may be (pre)configured.

In an example, as shown in FIG. 23 , a D2D resource pool may be to divide a bandwidth into multiple subchannels, wherein each transmitter of a number of neighboring transmitters may select one or more subchannels to transmit a signal. Subchannel selection may be based on received energy measurements and/or control channel decoding. As an example, a UE may identify which subchannel is going to be used by other UE based on control channel decoding as well as an energy measurement for each subchannel. Here, a limit on system performance may be imposed by in-band emissions. An in-band emission (IBE) is interference caused by one transmitter transmitting on one subchannel and imposed on another transmitter transmitting to a receiver on another subchannel. FIG. 23 is a diagram illustrating an in-band emissions model. Referring to FIG. 23 , the plot of the in-band emissions model shows that nearby subchannels as well as other subchannels (e.g., I/Q or image subchannels) experience more interference.

In an example, when the D2D UE operates in the cellular network, the power radiated by the D2D UE may cause serious interference to the cellular communication. In particular, when a D2D UE uses only some frequency resources in a particular slot or subframe, the inband emission of the power radiated by the D2D UE may cause serious interference to the frequency resources used by the cellular UE. To prevent this problem, the D2D UE may perform a cellular pathloss-based power control. At this time, the parameters (e. g. P0 or alpha) used for power control may be configured by the base station.

In an example, in a D2D communication, the transmission UE may correspond to a half-duplex UE which is unable to perform reception at the time of performing transmission. In particular, the transmission UE may fail to receive the transmission of the different UE due to the half-duplex problem. To mitigate half duplex problem, different D2D UEs performing communication need to transmit signals at least one or more different time resources.

In an example, D2D operation may have various advantages in that it is communication between devices in proximity. For example, D2D UE has a high transfer rate and a low delay and may perform data communication. Furthermore, in D2D operation, traffic concentrated on a base station may be distributed. If D2D UE plays the role of a relay, it may also play the role of extending coverage of a base station.

In an example, as shown in FIG. 24 , the D2D communication may be expanded and/or applied to signal transmission and/or reception between vehicles. Vehicle-related communication may be referred to as vehicle-to-everything (V2X) communication. In V2X, the term ‘X’ refers to a pedestrian (communication between a vehicle and a device carried by an individual (e.g.: handheld terminal carried by a pedestrian, cyclist, driver or passenger), in this case, V2X may be indicated V2P), a vehicle (communication between vehicles) (V2V), an infrastructure/network (communication between a vehicle and a roadside unit (RSU)/network (e.g., RSU is a transportation infrastructure entity (e.g., an entity transmitting speed notifications) implemented in a base station or a stationary UE)) (V2I/N), and so on. For V2X communication, a vehicle, an RSU and a handheld device may be equipped with a transceiver. FIG. 23 illustrates a diagram of V2X communication.

In an example, V2X communication may be used to indicate warnings for various events such as safety and the like. For example, information on an event occurring on a vehicle or road may be notified to another vehicle or pedestrians through V2X communication. For example, information on a warning of a traffic accident, a change of a road situation, or an accident occurrence may be forwarded to another vehicle or pedestrian. For example, a pedestrian, who is adjacent to or crossing a road, may be informed of information on vehicle approach.

In an example, in V2X communication, one challenge may be to avoid collisions and guarantee a minimum communication quality even in dense UE scenario. Wireless congestion control may represent a family of mechanisms to mitigate such collisions by adjusting communication parameter to control the congestion level on the vehicular wireless channel and guarantee reliable V2X communications. In an implementation of existing technologies, a wireless device may measure the following two metrics to characterize the channel state and allow the wireless device to take necessary actions: 1) channel busy radio (CBR): defined as the portion (or number) of subchannels in the resource pool whose RSSI measured exceeds a pre-configured threshold, wherein the total frequency resources may be divided into a given number of subchannels. Such metric may be sensed over the last 100 subframes (where the definition of “subframe” in LTE may be used). It may provide an estimation on the total state of the channel. 2) Channel occupancy ratio (CR): calculated at subframe n, it is defined as the total number of subchannels used for its transmissions in subframes [n−a, n−1] and granted in subframes [n, n+b] divided by the total number of subchannels within [n−a, n+b]. a and b are determined by the station with the limitation of a+b+1=1000, a≥500. The CR may provide an indication on the channel utilization by the transmitter itself. For each interval of CBR values, a CR limit may be defined as a footprint that the transmitter should not exceed. This CR limit may be configured by a base station per a CBR range and packet priority. For example, if a high CBR is observed, a low CR limit may be configured, and a low CR limit may be configured for a low packet priority. When the station decides to transmit a packet, it maps its CBR value to the correct interval to get the corresponding CR limit value. If its CR is higher than the CR limit, the wireless device may have to decrease its CR below that limit. To reduce the CR, it may be up to each implementation to decide which technique(s) to use. In an example, the following options to accommodate CR limit may be taken into account: 1) drop packet retransmission: if the retransmission feature is enabled, the station may disable it. 2) drop packet transmission: the station simply drops the packet transmission (including the retransmission if enabled). This is one of the simplest techniques. 3) adapt the MCS: the wireless device may reduce its CR by augmenting the MCS index used. This may reduce the number of subchannels used for the transmission. However, increasing the MCS reduces the robustness of the message, and thus reduces the range of the message. 4) adapt transmission power: the station may reduce its transmission power. Consequently, the overall CBR in the area may be reduced, and the value of CR limit might be increased.

In an example, in open loop MIMO, preferred PMI may not be indicated by receiver. In this case, a cyclic delay diversity (CDD) may be considered to enhance the decoding performance. CDD may involve transmitting the same set of a different delay on each antenna. The delay may be applied before the cyclic prefix is added, thereby guaranteeing that the delay may be cyclic over the FFT size. This gives CDD its name. Adding a time delay may be identical to applying a phase shift in the frequency domain. As the same time delay is applied to all subcarriers, the phase shift will increase linearly across the subcarriers with increasing subcarrier frequency. Therefore, each subcarrier may experience a different beamforming pattern as the non-delayed subcarrier from one antenna interferes constructively od destructively with the delayed version from another antenna. The diversity effect of CDD therefore arises from the fact that different subcarriers will pick out different spatial paths in the propagation channel, thus increasing the frequency-selectivity of the channel. The channel coding, which is applied to a whole transport block across the subcarriers, ensures that the whole transport block benefits from the diversity of spatial paths. The general principle of the CDD technique is illustrated in FIG. 25 . The fact that the delay is added before the CP means that any delay value may be used without increasing the overall delay spread of the channel. If the delay value is greater than CP length, the additional RS needs to be transmitted to estimate channel of delayed version differently. To distinguish between the two cases, a scheme that uses a delay shorter than the CP length is a small delay CDD (SD-CDD), and another scheme that requires an additional RS with a delay larger than the CP length is called a large delay CDD (LD-CDD).

In an example, as shown in FIG. 29 , FIG. 30 , FIG. 31 and/or FIG. 32 , one or more wireless devices (e.g., user equipment, UE, device, etc.) may be served by a first base station (e.g., gNB1, gNB, eNB, access node, access network, etc.). The first base station may have a connection with a second base station (e.g., gNB2, gNB, eNB, access node, access network, etc.). The connection may comprise a direct connection (e.g., Xn interface, X2 interface, etc.) and/or an indirect connection (e.g., comprising one or more N2 or S1 interfaces) via one or more core network nodes (e.g., AMF, MME, etc.). The first base station may serve a first cell. The first cell may comprise (e.g., operate based on) a plurality of beams comprising a first beam and/or a second beam. The first base station may comprise a first distributed unit (e.g., DU of gNB1, gNB-DU1, gNB-DU, base station DU, DU, etc.) and/or a first central unit (e.g., CU of gNB1, gNB-CU1, gNB-CU, base station CU, CU, etc.). The second base station may comprise a second distributed unit (e.g., DU of gNB2, gNB-DU2, gNB-DU, base station DU, DU, etc.) and/or a second central unit (e.g., CU of gNB2, gNB-CU2, gNB-CU, base station CU, CU, etc.). In an example, the second base station may serve a first wireless device. In the present disclosure, the first base station may be interpreted as the first central unit, and/or the second base station may be interpreted as the second central unit.

In an example, as shown in FIG. 29 , the first base station may determine, combined resource information of the first cell. The combined resource information may comprise a combined RSSI. The first base station may send, to the second base station, an information message comprising the combined resource information. The first base station may receive, from the second base station, a request message (e.g., handover request message, secondary node addition request message, secondary node modification request message, etc.) based on the combined resource information. The request message may indicate a request of resource configuration (e.g., handover, secondary cell group (SCG) configuration, etc.) of the first cell for the first wireless device.

In an example, the first base station may receive resource information from one or more wireless devices. The first base station may determine, based on the resource information, combined resource information of the first cell. The combined resource information may be resource status information of one or more cells and/or a resource pool configured for the first cell and/or the one or more cells. The combined resource information may comprise at least one of: a combined RSSI, a combined CBR, a combined CR, and/or the like. In an example, as shown in FIG. 31 and/or FIG. 32 , the combined resource information may be for at least one sidelink of at least one wireless device and/or may be for an unlicensed spectrum. The first base station may send, to the second base station, an information message comprising the combined resource information. In an example, the second base station may determine, based on the resource information, to initiate a handover (e.g., resource configuration: handover, secondary cell group configuration, etc.) of the first wireless device to the first cell or not to initiate a handover (e.g., not perform a resource configuration: handover, secondary cell group configuration, etc.) of the first wireless device to the first cell. If the second base station determine to initiate a handover (e.g., resource configuration: handover, secondary cell group configuration, etc.) of the first wireless device to the first cell, the second base station may send, to the first base station, a handover request message (e.g., or a secondary node addition/modification request message) for the handover (e.g., for the resource configuration and/or for the secondary cell group configuration) of the first wireless device. The handover request message may indicate a request of resource configuration (e.g., handover, secondary cell group configuration, etc.) of the first cell for the first wireless device. In an example, if the second base station determine not to initiate a handover (e.g., resource configuration: handover, secondary cell group configuration, etc.) of the first wireless device to the first cell, the second base station may send, to a third base station and based on the determining, a second handover request message (e.g., or a second secondary node addition/modification request message) for a second handover (e.g., second resource configuration: handover, secondary cell group configuration, etc.) of the first wireless device to a second cell.

In an example, the first base station may receive resource information from one or more wireless devices. In an example, the first base station may receive, from the one or more wireless devices, at least one measurement report (e.g., radio resource control (RRC) message) comprising the resource information. In an example, the receiving the resource information may comprise receiving via at least one of: a radio resource control (RRC) message (e.g., the at least one measurement report); a medium access control layer indication (e.g., medium access control control element, MAC CE); a physical layer indication (e.g., uplink control information, UCI); and/or the like.

The at least one measurement report may be based on at least one measurement configuration (e.g., via RRC reconfiguration message, RRC resume message, RRC reestablishment message, RRC setup message, etc.) transmitted by the first base station to the one or more wireless devices. The one or more wireless devices may send/transmit the at least one measurement report based on the at least one measurement configuration received from the first base station. The at least one measurement configuration may comprise at least one of: RSSI measurement timing configuration (RMTC) configurations (e.g., rmtc-Config; parameters applicable to RSSI and/or channel occupancy measurement on a carrier frequency indicated by carrierFreq); RMTC period (e.g., rmtc-Period; indicating an RMTC periodicity for a frequency; value ms40 may corresponds to 40 ms periodicity, ms80 may correspond to 80 ms periodicity, etc.); RMTC subframe offset (e.g., rmtc-SubframeOffset; indicating an RMTC subframe offset for a frequency; value of the RMTC subframe offset may be smaller than a value of the RMTC period; for inter-frequency measurements, RMTC subframe offset may be optional present; if RMTC subframe offset is not configured, a wireless device may choose a random value as RMTC subframe offset for measurement duration which may be selected to be between 0 and a configured RMTC period); and/or the like. The at least one measurement configuration may comprise synchronization signal RSSI measurement parameters (e.g., SS-RSSI-Measurement) indicating one or more measurement slots (e.g., measurementSlots; bit string with size 1 . . . 80; equal to a number of slots in a configured SMTC window that may be determined by a ssb-duration and/or by a subcarrierSpacingSSB), ending symbol (e.g., endSymbol; integer value: 0 . . . 3), and/or the like. The ending symbol (e.g., endSymbol) may indicate that within a slot that is configured for RSSI measurements (e.g., measurementSlots) a wireless device may measure an RSSI from symbol 0 to symbol of the ending symbol (e.g., the endSymbol). The one or more measurement slots (e.g., measurementSlots) may indicate slots in which a wireless device may perform RSSI measurements. The first (left-most/most significant) bit in the bitmap of the one or more measurement slots may correspond to the first slot in an SMTC window, the second bit in the bitmap of the one or more measurement slots may corresponds to the second slot in the SMTC window, and/or the like. A wireless device may measure in slots for which a corresponding bit in the bitmap of the one or more measurement slots may be set to 1. The at least one measurement configuration may comprise an RSSI range (e.g., RSSI-Range; integer value of 0 . . . 76) indicating a value range used in RSSI measurements and thresholds. The at least one measurement configuration may comprise a channel occupancy threshold value (e.g., channelOccupancyThreshold) indicating an RSSI threshold that may be used for channel occupancy evaluation.

In an example, the resource information (e.g., the at least one measurement report) may comprise at least one of: an RSSI (e.g., measResultForRSSI); a channel busy ratio (CBR); a channel occupancy ratio (CR); and/or the like. The RSSI (e.g., measResultForRSSI) may comprise an RSSI result (e.g., rssi-Result; indicating RSSI-Range), channel occupancy information (e.g., channelOccupancy; integer value of 0 . . . 100), and/or the like. The RSSI result may indicate a measured RSSI result in dBm. The channel occupancy information (e.g., channelOccupancy) may indicate a percentage of samples when an RSSI was above the channel occupancy threshold value (e.g., channelOccupancyThreshold) for an associated reportConfig of the at least one measurement configuration.

In an example, the RSSI may comprise a combination (e.g., average, linear average) of a total received power (e.g., in [W]) observed in a configured OFDM symbol and/or in the measurement bandwidth over N number of resource blocks, by a wireless device from transmission sources (e.g., all sources), including co-channel serving and/or non-serving cells, adjacent channel interference, thermal noise, and/or the like. In an example, higher layers (e.g., RRC layer, MAC layer, etc.; e.g., via the at least one measurement configuration) may indicate a measurement duration and/or which OFDM symbol(s) may be measured by a wireless device. A reference point for the RSSI may be an antenna connector of a wireless device. If receiver diversity is in use by a wireless device, a reported value may not be lower than a corresponding RSSI of individual diversity branches. A wireless device may measure the RSSI for RRC_CONNECTED intra-frequency, RRC_CONNECTED inter-frequency, RRC_Idle intra/inter-frequency, RRC Inactive intra/inter-frequency, and/or the like. In an example, the RSSI may represent relative quality of a received signal on a wireless device. The RSSI may indicate a power level being received. A higher RSSI value may indicate a stronger received signal. When measured in negative numbers, a number that is closer to zero may mean better signal. As an example, −50 may indicate a good signal, −75 may indicate reasonable, and/or −100 may indicate no signal.

In an example, the channel busy ratio (CBR) measured in subframe n may be defined as follows: for physical sidelink shared channel (PSSCH), a portion of sub-channels in a resource pool (e.g., sidelink resource pool) whose S-RSSI measured by a wireless device exceeds a (pre)configured threshold sensed over subframes [n−100, n−1]; for physical sidelink control channel (PSCCH), in a pool (pre)configured such that PSCCH may be transmitted with corresponding PSSCH in non-adjacent resource blocks, a portion of resources of a PSCCH pool whose S-RSSI measured by a wireless device exceeds a (pre)configured (e.g., received from the first base station) threshold sensed over subframes [n−100, n−1], assuming that the PSCCH pool may comprise resources with a size of two consecutive PRB pairs in a frequency domain; and/or the like. A wireless device may measure the CBR for RRC_IDLE intra-frequency, RRC_IDLE inter-frequency, RRC_CONNECTED intra-frequency, RRC_CONNECTED inter-frequency, and/or the like. A subframe index may be based on physical subframe index.

In an example, the channel occupancy ratio (CR) evaluated at subframe n may be defined as a total number of sub-channels used for transmissions in subframes [n−a, n−1] and/or granted in subframes [n, n+b] divided by a total number of configured sub-channels in a transmission pool over [n−a, n+b]. A wireless device may measure the CR for RRC_IDLE intra-frequency, RRC_IDLE inter-frequency, RRC_CONNECTED intra-frequency, RRC_CONNECTED inter-frequency, and/or the like. In an example, “a” may be a positive integer and/or “b” may be 0 or a positive integer. In an example, “a” and/or “b” may be determined by wireless device implementation (e.g., with a+b+1=1000, a>=500). In an example, n+b may not exceed the last transmission opportunity of a grant for a current transmission. CR may be evaluated for each (re)transmission. In evaluating CR, a wireless device may assume a transmission parameter used at subframe n is reused according to existing grant(s) in subframes [n+1, n+b] without packet dropping. A subframe index may be based on physical subframe index. CR may be determined/computed per priority level (e.g., resource priority level, UE priority level, logical channel priority level, etc.).

In an example, the resource information may be for a sidelink (e.g., via a PC5 interface) of the one or more wireless devices. The resource information may be for a resource pool for a sidelink of the one or more wireless devices. In an example, the one or more wireless device may receive (e.g., from the first base station) configuration parameters for the sidelink. The configuration parameters may comprise information of the resource pool used (e.g., and/or allowed to be used) by the one or more wireless devices for communication via the sidelink. The one or more wireless devices may receive the configuration parameters for the sidelink via at least one system information block (e.g., SIB18, SIB19, SIB21, SIB26, etc.) and/or at least one RRC message (e.g., from the first base station). The information of the resource pool and/or the configuration parameters may comprise at least one of: sidelink carrier frequency information list (e.g., sidelink carrier frequency, SL-CarrierFreq, carrierFreq, etc.); sidelink discovery resource information (e.g., discRxResourcesFreq, SL-DiscRxPoolList, discTxResourcesFreq, SL-DiscTxPoolList, etc.); common resource pool information (e.g., commTxPoolNormalCommonExt, v2x-CommTxPoolNormalCommon, p2x-CommTxPoolNormalCommon, v2x-CommTxPoolExceptional, v2x-CommRxPool, etc.); resource selection configurations (e.g., v2x-ResourceSelectionConfig, SL-CommTxPoolSensingConfig, etc.); zone configuration (e.g., zoneConfig, SL-ZoneConfig, etc.); CBR configuration parameters (e.g., the (pre)configured threshold for CBR determination); and/or the like. In an example, the information of the resource pool may comprise frequency information, subframe information, slot information, resource periodicity, resource timing offset (e.g., offset from SFN #0), bandwidth information, and/or bandwidth part information of the resource pool for the sidelink.

The sidelink of the one or more wireless devices may be for device-to-device (D2D) communication, V2X communication, machine type communication, Internet-of-things communication, drone communication, and/or the like. A wireless device of the one or more wireless devices may communicate with another wireless device of the one or more wireless devices via the sidelink. In an example, the wireless device of the one or more wireless devices may be in an RRC connected state, in an RRC idle, and/or in an inactive state; and/or the like. A wireless device of the one or more wireless devices may communicate via the sidelink with a third wireless device that may be at least one of: served by the first base station; served at the first cell; served by a third base station; served by a third cell; in an RRC connected state; in an RRC idle/inactive state; and/or the like. The resource information may be for sidelink communication during the mode1, the mode2, and/or the mode3.

In an example, the resource information may be for an unlicensed spectrum of the first cell. The first cell may use/employ an unlicensed spectrum. In an example, the first cell may be a license-assisted-access (LAA) cell (e.g., LAA LTE cell, LAA NR-U cell, etc.), a stand-alone unlicensed cell (e.g., NR-U stand-alone cell, LTE-U stand-alone cell, etc.), and/or the like. The resource information may be for the first cell (e.g., unlicensed cell) and/or an unlicensed frequency resource set that may be configured by the first base station with frequency information, subframe information, slot information, resource periodicity, resource timing offset (e.g., offset from SFN #0), bandwidth information, and/or bandwidth part information. The resource information may be associated with communication (e.g., via a Uu interface) between the one or more wireless device and the first base station. The resource information may be for sidelink communication using/employing an unlicensed spectrum.

In an example, the first central unit of the first base station may receive, from the first distributed unit of the first base station, second resource information comprising a second RSSI (e.g., second CBR, second CR, etc.) of the first cell. The second resource information may comprise at least one of: a RSSI; a channel busy ratio (CBR); a channel occupancy ratio (CR); and/or the like. The combined resource information may be based on the second resource information. The second resource information may comprise the resource information of the one or more wireless devices. The first distributed unit may receive the resource information of the one or more wireless devices from the one or more wireless devices via a lower layer (e.g., MAC/PHY layer, MAC CE, UCI, etc.). The first distributed unit may combine (e.g., average) the resource information of the one or more wireless device, and/or send the combined resource information to the first central unit via the second resource information (e.g., via F1 interface). In an example, the receiving, by the first base station, the resource information may comprise at least one of: receiving, by the first distributed unit of the first base station from the one or more wireless devices, the resource information; and/or sending, by the first distributed unit to the first central unit of the first base station, the resource information. The first central unit (e.g., the first base station) may initiate a handover of the one or more wireless device to a third cell based on the second resource information. If the resource pool and/or the one or more resource pools for sidelink communication at the first cell are congested (e.g., the RSSI is larger than a first threshold value, the CBR is larger than a threshold value, the CR is larger than a threshold value, etc.), the first central unit (e.g., the first base station) may handover the one or more wireless devices to a neighboring cell.

In an example, the first base station may determine, based on the resource information, combined resource information of the first cell. In an example, the first base station may determine, based on the resource information and/or the second resource information, combined resource information of the first cell. In an example, the first base station may determine, based on the resource information and/or the second resource information, combined resource information of the resource pool for the sidelink. The combined resource information may comprise at least one of: a combined RSSI, a combined CBR, a combined CR, and/or the like. The resource pool of the sidelink may be shared for multiple sidelinks of multiple wireless devices. In an example, the determining the combined resource information may comprise combining/averaging one or more resource information for at least one of: resources in a time duration (e.g., 10 seconds, 1 second, etc.); and/or resources in a first bandwidth (e.g., carrier, band, bandwidth part, frequency band of the resource pool, one or more resource pools). In an example, the determining the combined resource information may comprise combining/averaging one or more resource information for one or more sidelinks received from at least one wireless device. The first base station (e.g., and/or the first base station central unit) may receive, from at least one wireless device, one or more resource information (e.g., the resource information, RSSI, CBR, CR, etc.) for one or more sidelinks using the resource pool, and/or may combine/average the one or more resource information that is determined/measured by the at least one wireless device for the time duration and/or that is received by the first base station for the time duration.

In an example, the combined resource information may comprise at least one of: a combined RSSI, a combined CBR, and/or a combined CR of the first cell. In an example, the combined resource information may comprise at least one of: a combined RSSI, a combined CBR, and/or a combined CR of one or more resource pools (e.g., comprising the resource pool). In an example, the combined resource information may comprise the resource information of the one or more wireless devices.

In an example, the combined RSSI of the first cell, of the resource pool, and/or of the one or more resource pools may indicate a combined (e.g., averaged) RSSI value per resource block, per symbol, per time interval, and/or the like (e.g., combined/average RSSI value of multiple sidelinks for a resource block, of a symbol and/or of a time interval; e.g., RSSI table comprising combined RSSI of each resource block, each symbol, and/or each time interval of the resource pool and/or the one or more resource pools). In an example, the combined RSSI of the first cell, of the resource pool, and/or of the one or more resource pools may indicate a combined RSSI of resource blocks, of symbols, and/or of time intervals for the resource pool, the first cell, and/or the one or more resource pools (e.g., combined RSSI for resource blocks, symbols, and/or time intervals for the resource pool and/or the one or more resource pools).

In an example, the combined resource information may be for the sidelink at the first cell. In an example, the combined resource information may be for the resource pool for the sidelink at the first cell. In an example, the combined resource information may be for the resource pool for the sidelink at one or more cells. In an example, the combined resource information may be for the unlicensed spectrum of the first cell. The combined resource information may be for at least one sidelink of at least one wireless device. In an example, the combined resource information may comprise at least one of: a first combined resource information of a first bandwidth part of the first cell; and/or a second combined resource information of a second bandwidth part of the first cell. In an example, the combined resource information may comprise at least one of: a third combined resource information of at least one first beam of the first cell; and/or a fourth combined resource information of a at least one second beam of the first cell. In an example, the combined resource information may comprise one or more identifiers of the one or more wireless devices. In an example, the combined resource information may comprise a resource pool index indicating the resource pool for the sidelink at the first cell, one or more resource pool indexes indicating the one or more resource pool, and/or a cell identifier indicating the first cell.

In an example, the first base station may send, to the second base station (e.g., via at least one Xn/X2 message and/or at least one N2/S1 message; e.g., via load information message, resource status update message, NG-RAN node configuration update message, eNB configuration update message, etc.), the information of the resource pool for sidelink communications at the first cell. The information of the resource pool may comprise at least one of: sidelink carrier frequency information list (e.g., sidelink carrier frequency, SL-CarrierFreq, carrierFreq, etc.); sidelink discovery resource information (e.g., discRxResourcesFreq, SL-DiscRxPoolList, discTxResourcesFreq, SL-DiscTxPoolList, etc.); common resource pool information (e.g., commTxPoolNormalCommonExt, v2x-CommTxPoolNormalCommon, p2x-CommTxPoolNormalCommon, v2x-CommTxPoolExceptional, v2x-CommRxPool, etc.); resource selection configurations (e.g., v2x-ResourceSelectionConfig, SL-CommTxPoolSensingConfig, etc.); zone configuration (e.g., zoneConfig, SL-ZoneConfig, etc.); CBR configuration parameters (e.g., the (pre)configured threshold for CBR determination); and/or the like. In an example, the information of the resource pool may comprise frequency information, subframe information, slot information, resource periodicity, resource timing offset (e.g., offset from SFN #0), bandwidth information, and/or bandwidth part information of the resource pool for the sidelink. In an example, the second base station may configure at least one resource pool for a second cell (e.g., for at least one sidelink of the second cell) of the second base station based on the information of the resource pool. The second base station may configure the at least one resource pool for the second cell to be (e.g., partially or fully) overlapped with the resource pool at the first cell and/or the first base station. The overlapped resource pool of the first cell and the second cell may increase sidelink communication reliability of wireless devices when the wireless devices handover between the first cell and the second cell (e.g., by enabling the wireless devices to use same resources before and after the handover; e.g., by reducing transition time of the wireless devices between different radio resources) and/or when a wireless device at the first cell performs a sidelink communication with another wireless device at the second cell.

In an example, the first base station may send, to the second base station, an information message comprising the combined resource information of the first cell, the resource pool, and/or the one or more resource pools. In an example, the information message may comprise at least one of: a load information message; a resource status update message; a resource status information message; and/or the like. The first base station may send the information message to the second base station via the Xn/X2 interface and/or one or more N2/S1 interfaces (e.g., via at least one AMF/MME). In an example, the second base station may send, to the first base station, an information request message requesting the combined resource information, and the first base station may send the information message based on the information request message. The information request message may indicate a periodicity and/or conditions (e.g., event; e.g., RSSI threshold, CBR threshold, CR threshold, etc.) to send the information. The first base station may send, to the second base station, an information request response message in response to the information request message, and/or send, to the second base station, the information message with the periodicity and/or when one or more of the conditions (e.g., the event) satisfy/meet/happen. The information request message may comprise the resource pool index indicating the resource pool for the sidelink communication at the first cell. The information request message may comprise the cell identifier indicating the first cell.

In an example, as shown in FIG. 30 , the first distributed unit of the first base station may receive, from the first central unit of the first base station, the combined resource information of the first cell (e.g., the resource pool and/or the one or more resource pools). The first distributed unit may determine, based on the combined resource information, radio resource configuration parameters (e.g., resource pool configuration parameters for sidelinks) for a second wireless device (e.g., for sidelink of the second wireless device). The first distributed unit may assign resources for wireless devices (e.g., operating with mode 1 resource allocation) using a sidelink based on the combined resource information. The first distributed unit may send, to the first central unit, the radio resource configuration parameters for the second wireless device. The first central unit (e.g., the first base station) may send, to the second wireless device, the radio resource configuration parameters via at least one RRC message.

In an example, as shown in FIG. 30 , a second distributed unit of the second base station may receive, from a second central unit of the second base station, the combined resource information of the first cell (e.g., the resource pool and/or the one or more resource pools) of the first base station. The second distributed unit may determine, based on the combined resource information, second radio resource configuration parameters (e.g., resource pool configuration parameters for sidelinks) for a third wireless device (e.g., for sidelink of the third wireless device). The second distributed unit may assign resources for wireless devices (e.g., operating with mode 1 resource allocation) using a sidelink based on the combined resource information. The second distributed unit may send, to the second central unit, the second radio resource configuration parameters for the third wireless device. The second central unit (e.g., the second base station) may send, to the third wireless device, the second radio resource configuration parameters via at least one RRC message.

In an example, the second base station may receive, from a first wireless device, at least one measurement report (e.g., via at least one uplink RRC message) comprising measurement results of the first cell and/or one or more cells. In an example, the first wireless device may use a sidelink communication (e.g., V2X communication, D2D communication, URLLC service communication, IoT/MTC communication, etc.) with one or more second wireless devices. In an example, the first wireless device may be capable to use an unlicensed spectrum (e.g., capable of listen-before-talk (LBT) procedure). The measurement results may comprise RSRP/RSRQ of the first cell of the first base station and/or the second cell of the second base station. In an example, the first wireless device may send/transmit the at least one measurement report based on the receiving at least one beam (e.g., SS and/or CSI-RS) of the first cell. The measurement results may comprise at least one of: at least one received power (e.g., RSRP) of the at least one beam (e.g., SS and/or CSI-RS); at least one received quality (e.g., RSRQ) of the at least one beam (e.g., SS or CSI-RS); and/or the like. The measurement results may comprise a combined RSRP and/or a combined RSRQ (e.g., layer 3 measurement result) of the at least one beam of the first cell. The combined RSRP may be/indicate an RSRP of the first cell. The combined RSRQ may be/indicate an RSRQ of the first cell. The measurement results may comprise one or more RSRPs and/or one or more RSRQs of one or more cells of the first base station and/or the second base station. In an example, the at least one measurement report may comprise an RRC layer message. In an example, the at least one measurement result may be based on measurement configurations (e.g., meas-Config) that the first wireless device receives from the second base station via at least one RRC message (e.g., RRC reconfiguration message, RRC reestablishment message, RRC resume message, RRC setup message, etc.).

In an example, as shown in FIG. 33 and/or FIG. 34 , the second base station may determine, based on the at least one measurement report (e.g., the measurement results) and/or the information message (e.g., the combined resource information and/or the resource information), to perform a request of radio resource configuration initiation (e.g., handover to the first cell, secondary node addition/modification (e.g., SCG configuration), etc.) for the first cell of the first base station for the first wireless device. The radio resource configuration initiation may be at least one of: the handover of the first wireless device to the first cell; the secondary node addition/modification (e.g., SCG configuration) for the first wireless device with the first base station (e.g., configuring the first cell as a secondary cell group (SCG) of the first wireless device); and/or the like. The secondary node addition/modification may be and/or may be part of an SCG change procedure. The secondary node addition/modification may comprise configuring the first cell as an SCG (e.g., a primary secondary cell (PScell) and/or a secondary cell (Scell)) for the first wireless device.

In an example, the second base station may determine to perform the request of the radio resource configuration initiation in response to resource status of the resource pool for sidelink, the first cell (e.g., for sidelink and/or using the unlicensed spectrum), and/or the one or more cells being enough (e.g., the combined RSSI is equal to or smaller than a RSSI threshold value; the combined CBR is equal to or smaller than a CBR threshold value; the combined CR is equal to or larger than a CR threshold; etc.) to support services that the first wireless device needs/requires/uses.

In an example, if the first wireless device uses a sidelink communication with one or more wireless devices and if the resource pool of the first base station (e.g., the first cell and/or the one or more cells) is in relatively low load status (e.g., not congested; the combined RSSI is equal to or smaller than a RSSI threshold value; the combined CBR is equal to or smaller than a CBR threshold value; and/or the combined CR is equal to or larger than a CR threshold) to serve the sidelink communication of the first wireless device, the second base station may determine to perform the request of the radio resource configuration initiation for the first wireless device. In an example, if the unlicensed spectrum of the first base station (e.g., the first cell and/or the one or more cells) is in relatively low load status (e.g., not congested; the combined RSSI is equal to or smaller than a RSSI threshold value; the combined CBR is equal to or smaller than a CBR threshold value; and/or the combined CR is equal to or larger than a CR threshold) to serve the first wireless device, the second base station may determine to perform the request of the radio resource configuration initiation for the first wireless device. In an example, if the RSRP and/or the RSRQ of the first cell received via the at least one measurement report is equal to or larger than a threshold power value, the second base station may determine to perform the request of the radio resource configuration initiation for the first wireless device.

In an example, the second base station may determine, based on the at least one measurement report and/or the information message (e.g., the resource information), to not perform the request of the radio resource configuration initiation (e.g., handover to the first cell, SCG configuration, secondary node addition/modification, etc.) of the first cell for the first wireless device. In an example, the second base station may determine to not perform the request of the radio resource configuration initiation in response to resource status of the resource pool for sidelink, the first cell (e.g., for sidelink and/or using the unlicensed spectrum), and/or the one or more cells being not enough (e.g., congested; the combined RSSI is equal to or larger than a RSSI threshold value; the combined CBR is equal to or larger than a CBR threshold value; the combined CR is equal to or smaller than a CR threshold; etc.) to support services that the first wireless device needs/requires/uses.

In an example, as shown in FIG. 33 and/or FIG. 34 , the second base station may send, to the first base station and/or based on the determining to perform the request of the radio resource configuration initiation (e.g., the handover, the SCG configuration, secondary node addition/modification, etc.), a request message. The request message may be based on the combined resource information and/or the information message. In an example, the first base station may receive, from the second base station, the request message based on the combined resource information and/or the information message. The request message may indicate the request of the radio resource configuration initiation of the first cell and/or the one or more cells for the first wireless device. In an example, if the second base station determines to perform the request of the radio resource configuration initiation (e.g., handover to the first cell, secondary cell group configuration for a secondary cell group comprising the first cell, etc.) of the first wireless device for the first cell and/or the one or more cells, the second base station may send, to the first base station, the request message (e.g., a handover request message, a secondary node addition/modification request message, etc.) for the radio resource configuration initiation of the first wireless device. The secondary node addition request message may be at least one of an S-node addition request message and/or an SeNB addition request message. The secondary node modification request message may be at least one of an S-node modification request message and/or an SeNB modification request message. In an example, the radio resource configuration initiation of the first cell and/or the one or more cells for the wireless device may comprise at least one of: a handover to the first cell; configuration of a secondary cell group (SCG) comprising the first cell; and/or the like.

In an example, the second base station may send the request message to the first base station via the direct interface (e.g., the Xn interface and/or the X2 interface) between the first base station and the second base station. In an example, the second base station may send, to the first base station, indication of the request of the radio resource configuration initiation (e.g., the handover or the secondary node addition/modification) via the indirect connection (e.g., comprising the one or more N2 or S1 interfaces) through the one or more core network nodes (e.g., AMF, MME, etc.). In an example, the second base station may send, to the AMF (e.g., MME), a handover required message for the handover of the first wireless device, and/or the AMF (e.g., MME) may send, to the first base station and based on the handover required message, an S1/N2 handover request message for the handover of the first wireless device.

In an example, the request message may comprise the measurement results of the at least one measurement report. The request message may comprise at least one of: a UE identifier of the first wireless device; a cell identifier (e.g., physical cell identifier, PCI, cell global identifier, CGI, etc.) of the first cell (e.g., target cell); security capability information and/or security information of the first wireless device; PDU session information (e.g., PDU session list, QoS flow list, QoS, S-NSSAI, NSSAI, etc.) of the first wireless device; RRC contexts (e.g., RRC configuration parameters; e.g., recommended RRC configuration parameters) of the first wireless device; and/or the like. In an example, the request message may comprise at least one of: sidelink resource configuration of the first wireless device at the second cell and/or the second base station, recommended sidelink resource configuration for the first wireless device at the first cell and/or the one or more cells, resource pool index of a sidelink resource pool (e.g., the resource pool of the first cell and/or the one or more cells) that the first wireless device uses at the second cell and/or the second base station and/or that the first wireless device is recommended to use at the first cell and/or the first base station, session configuration parameters (e.g., PDU session identifier, QoS configuration, QoS flow identifier, 5QI/QCI, ARP, priority information, latency, network slice information, S-NSSAI, NSSAI, reliability, etc.) of one or more PDU sessions (e.g., bearers, QoS flows, sidelink/PC5 sessions, etc.), security information, configured grant resource information (e.g., periodicity, timing offset, and/or size for sidelink communication), session tunnel endpoint identifier (e.g., for uplink/downlink), the at least one measurement report of the first wireless device, and/or the like.

In an example, if the second base station determines to not initiate a resource configuration (e.g., handover, secondary cell group configuration, etc.) of the first wireless device for the first cell and/or the one or more cells, the second base station may not send, to the first base station, the request message indicating the request of the radio resource configuration initiation of the first cell and/or the one or more cells for the first wireless device. The second base station may send, to a third base station and based on the determining to not initiate the resource configuration, a second request message (e.g., second handover request message, a second secondary node addition/modification request message, etc.) for a second resource configuration (e.g., handover, secondary cell group configuration, etc.) of the first wireless device for a second cell.

In an example, as shown in FIG. 33 and/or FIG. 34 , the first base station may send, to the second base station, a request acknowledge message indicating acceptance of the request of the radio resource configuration initiation for the first wireless device. The first base station may determine the acceptance of the request of the radio resource configuration initiation for the first wireless device based on resources of the resource pool, the first cell, and/or the one or more cells being available for the first wireless device (e.g., in low load status, not congested, enough system capacity, etc.). The first base station may determine the acceptance of the request of the radio resource configuration initiation for the first wireless device based on one or more parameters (e.g., information elements) of the request message being configurable at the first cell and/or the one or more cells. In an example, the first base station may send, to the second base station and in response to the request message and/or in response to determining to accept the request for the radio resource configuration initiation (e.g., the handover or the secondary node addition/modification) of the first wireless device, the request acknowledge message (e.g., a handover request acknowledge message, a secondary base station addition/modification request acknowledge message, etc.) comprising access information of the first cell and/or the one or more cells for the first wireless device. In an example, the second base station may receive, from the first base station, the handover request acknowledge message (e.g., for the handover) comprising the access information for the first cell and/or the one or more cells for the first wireless device. In an example, the second base station may receive, from the first base station, a configuration request acknowledge message (e.g., for the secondary node addition/modification acknowledge) comprising the access information for the first cell and/or the one or more cells for the first wireless device. The configuration request acknowledge message may comprise at least one of: the secondary node addition request acknowledge message (e.g., S-node addition request acknowledge message, SeNB addition request acknowledge message, etc.); the secondary node modification request acknowledge message (e.g., S-node modification request acknowledge message, SeNB modification request acknowledge message, etc.); and/or the like.

In an example, the first base station may send the request acknowledge message to the second base station via the direct interface (e.g., the Xn interface and/or the X2 interface) between the first base station and the second base station. In an example, the first base station may send indication of the request acknowledge of the radio resource configuration initiation (e.g., the handover, the SCG configuration, and/or the secondary node addition/modification) via the indirect connection (e.g., comprising the one or more N2 or S1 interfaces) through the one or more core network nodes (e.g., AMF, MME, etc.). In an example, the first base station may send, to the AMF, an S1/N2 handover request acknowledge message for the handover of the first wireless device, and/or the AMF may send, to the second base station and based on the handover request acknowledge message, an S1/N2 handover command message for the handover of the first wireless device.

In an example, the request acknowledge message may comprise at least one of: a UE identifier of the first wireless device; a cell identifier (e.g., physical cell identifier, PCI, cell global identifier, CGI, etc.) of the first cell (e.g., target cell); security capability information and/or security information of the first wireless device; PDU session information (e.g., accepted/setup/modified/rejected/released PDU session list, QoS flow list, QoS, S-NSSAI, NSSAI, etc.) of the first wireless device; RRC contexts (e.g., RRC configuration parameters that may be configured based on the measurement results of the first wireless device for the first cell and/or the one or more cells) of the first wireless device; and/or the like. The request acknowledge message may comprise random access configuration parameters for the first wireless device. In an example, the second base station may send, to the first wireless device, a handover command message that comprises the RRC configuration parameters (e.g., the RRC contexts and/or the random access configuration parameters) of the request acknowledge message.

In an example, if the first base station does not allow/admit/accept the request of the radio resource configuration initiation for the first wireless device (e.g., due to lack of resources to serve the first wireless device; lack of system capacity of the first base station; high load status of the resource pool, the first cell, and/or the one or more cells; based on access control polices of the first cell and/or the one or more cells; etc.), the first base station may send, to the second base station, a request acknowledge message (e.g., handover preparation failure message, secondary node addition/modification request reject message, etc.) indicating rejection of the request of the resource configuration for the first wireless device.

In an example, the first wireless device may perform a random access process (e.g., 4-step and/or 2-step random access) at the first cell and/or at the one or more cells by transmitting/sending one or more random access preambles to the first base station. The one or more random access preambles and/or random access resources for the one or more random access preambles may be configured via the request acknowledge message (e.g., the random access configuration parameters of the request acknowledge message).

In an example, the first base station may communicate packets (e.g., transport blocks) with the first wireless device via a Uu interface (e.g., using the unlicensed spectrum of the first cell and/or the one or more cells) based on an RRC connection that is established based on the random access process of the first wireless device. The first wireless device may transmit/receive, to/from one or more wireless devices, packets (e.g., transport blocks) via a sidelink (e.g., PC5 interface) that uses the resource pool at the first cell and/or the one or more cells. The first wireless device may report resource status of the resource pool and/or the Uu interface (e.g., using the unlicensed spectrum). The resource status may comprise a RSSI, a CBR, a CR, and/or the like.

In an example, as shown in FIG. 35 , a first sidelink wireless device may receive, from a second sidelink wireless device, resource information of a resource pool for a sidelink at a cell. In an example, the first sidelink wireless device may determine, based on the resource information, combined resource information of the cell. The combined resource information may comprise a combined RSSI. The first sidelink wireless device may send, to a second base station, an information message comprising the combined resource information. The combined resource information may comprise at least one of a combined CBR, a combined CR, and/or the like. The combined resource information may comprise the resource information of the resource pool. In an example, a first base station may serve the cell associated with the sidelink.

In an example, as shown in FIG. 36 , and/or FIG. 38 , a first base station may receive resource information from one or more wireless devices. The first base station may determine, based on the resource information, combined resource information of a first cell. The combined resource information may comprise a combined received signal strength indicator (RSSI). The first base station may send, to a second base station, an information message comprising the combined resource information. The first base station may receive, from the second base station, a request message based on the combined resource information. The request message may indicate a request of resource configuration of the first cell for a first wireless device.

In an example, the resource information may comprise at least one of: an RSSI; a channel busy ratio (CBR); a channel occupancy ratio (CR); and/or the like. The resource information may be for a sidelink of the one or more wireless device. The resource information may be for a resource pool for a sidelink of the one or more wireless device. The resource information may be for an unlicensed spectrum of the first cell. The first cell may use/employ an unlicensed spectrum.

In an example, the receiving the resource information may comprise receiving via at least one of: a radio resource control (RRC) message (e.g., a measurement report); a medium access control layer indication (e.g., medium access control control element, MAC CE); a physical layer indication (e.g., uplink control information, UCI); and/or the like.

In an example, a first central unit of the first base station may receive, from a first distributed unit of the first base station, second resource information comprising a second RSSI of the first cell. The second resource information may comprise at least one of: a RSSI; a channel busy ratio (CBR); a channel occupancy ratio (CR); and/or the like. The combined resource information may be based on the second resource information.

In an example, the receiving, by the first base station, the resource information may comprise at least one of: receiving, by a first distributed unit of the first base station from the one or more wireless devices, the resource information; and/or sending, by the first distributed unit to a first central unit of the first base station, the resource information. In an example, the first base station may send, to the second base station, information of a resource pool for sidelink communications at the first cell.

In an example, the combined resource information may comprise one or more identifiers of the one or more wireless devices. In an example, the combined resource information may comprise the resource information. In an example, the combined resource information may comprise at least one of: a combined channel busy ratio (CBR); a combined channel occupancy ratio (CR); and/or the like. In an example, the combined resource information may be for a sidelink at the first cell. In an example, the combined resource information may be for a resource pool for a sidelink at the first cell. In an example, the combined resource information may be for a resource pool for a sidelink at one or more cells of the first base station. In an example, the combined resource information may be for an unlicensed spectrum of the first cell. In an example, the combined resource information may comprise at least one of: a first combined resource information of a first bandwidth part of the first cell; and/or a second combined resource information of a second bandwidth part of the first cell.

In an example, the determining the combined resource information may comprise combining/averaging one or more resource information for at least one of: resources in a time duration; and/or resources in a first bandwidth.

In an example, the information message may comprise at least one of: a load information message; a resource status update message; a resource status information message; and/or the like. In an example, the request message may comprise at least one of: a handover request message; a secondary node addition request message; a secondary node modification request message; and/or the like.

In an example, the resource configuration of the first cell may comprise at least one of: a handover to the first cell; configuration of a secondary cell group (SCG) comprising the first cell; and/or the like.

In an example, as shown in FIG. 37 , and/or FIG. 39 , the second base station may receive, from the first wireless device, at least one measurement report comprising measurement results of the first cell. The second base station may determine, based on the at least one measurement report and the information message, the request of the resource configuration of the first cell for the first wireless device. The request message is based on the determining the request of the resource configuration.

In an example, a first distributed unit of the first base station may receive, from a first central unit of the first base station, the combined resource information of the first cell. The first distributed unit may determine, based on the combined resource information, radio resource configuration parameters for a second wireless device. The first distributed unit may send, to the first central unit, the radio resource configuration parameters for the second wireless device.

In an example, a second distributed unit of the second base station may receive, from a second central unit of the second base station, the combined resource information of the first cell. The second distributed unit may determine, based on the combined resource information, radio resource configuration parameters for a third wireless device. The second distributed unit may send, to the second central unit, the radio resource configuration parameters for the third wireless device.

In an example, the first wireless device may use a sidelink communication. In an example, the first base station may send, to the second base station, a request acknowledge message indicating acceptance of the request of the resource configuration for the first wireless device.

In an example, as shown in FIG. 37 , and/or FIG. 39 , a second base station may receive, from a first base station, combined resource information of a first cell of the first base station. The combined resource information may comprise a combined RSSI of at least one sidelink of at least one wireless device. The second base station may determine, based on the resource information, to initiate a handover of a first wireless device to the first cell. The second base station may send, to the first base station, a handover request message for the handover of the first wireless device.

In an example, a second base station may receive, from a first base station, combined resource information of a first cell of the first base station. The combined resource information may comprise a combined RSSI of at least one sidelink of at least one wireless device. The second base statin may determine, based on the resource information, not to initiate a handover of a first wireless device to the first cell. The second base station may send, to a third base station and based on the determining, a second handover request message for a second handover of the first wireless device to a second cell.

In an example, a first base station may determine, combined resource information of a first cell. The combined resource information may comprise a combined RSSI. The first base station may send, to a second base station, an information message comprising the combined resource information. The first base station may receive, from the second base station, a request message based on the combined resource information. The request message may indicate a request of resource configuration of the first cell for a first wireless device.

In an example, a first sidelink wireless device may receive, from a second sidelink wireless device, resource information of a resource pool for a sidelink at a cell. In an example, the first sidelink wireless device may determine, based on the resource information, combined resource information of the cell. The combined resource information may comprise a combined RSSI. The first sidelink wireless device may send, to a second base station, an information message comprising the combined resource information. The combined resource information may comprise at least one of a combined CBR, a combined CR, and/or the like. The combined resource information may comprise the resource information of the resource pool. In an example, a first base station may serve the cell associated with the sidelink.

FIG. 40 is a diagram of an aspect of an example embodiment of the present disclosure. At 4010, a first base station may receive resource information from one or more wireless devices. At 4020, the first base station may determine, based on the resource information, combined resource information associated with a first cell. The combined resource information may comprise a combined channel busy ratio of a sidelink resource pool. At 4030, the first base station may send, to a second base station, an information message comprising the combined resource information. At 4040, the first base station may receive, from the second base station, a request message requesting a resource configuration of the first cell for a wireless device. The request message may be based on the information message.

According to an example embodiment, the resource information may comprise a received signal strength indicator (RSSI). According to an example embodiment, the resource information may comprise a channel busy ratio (CBR). According to an example embodiment, the resource information may comprise a channel occupancy ratio (CR). The first base station may send, to the second base station, information of the sidelink resource pool for sidelink communications associated with the first cell. The combined resource information may comprise a received signal strength indicator (RSSI). The combined resource information may comprise a combined channel occupancy ratio (CR).

According to an example embodiment, the combined resource information may comprise a first combined resource information of a first bandwidth part of the first cell. According to an example embodiment, the combined resource information may comprise a second combined resource information of a second bandwidth part of the first cell.

According to an example embodiment, the first cell may use an unlicensed spectrum. The determining the combined resource information may comprise averaging one or more resource information for at least one of resources in a time duration and/or resources in a first bandwidth. According to an example embodiment, the resource configuration of the first cell for the wireless device may comprise a handover to the first cell. According to an example embodiment, the resource configuration of the first cell for the wireless device may comprise configuration of a secondary cell group comprising the first cell.

According to an example embodiment, a first central unit of the first base station may receive, from a first distributed unit of the first base station, second resource information. The second resource information may comprise a received signal strength indicator (RSSI). The second resource information may comprise a channel busy ratio (CBR). The second resource information may comprise a channel occupancy ratio (CR). The combined resource information may be based on the second resource information.

According to an example embodiment, a first distributed unit of the first base station may receive, from a first central unit of the first base station, the combined resource information of the first cell. The first distributed unit may assign, based on the combined resource information, radio resources for a second wireless device. 

What is claimed is:
 1. A method comprising: communicating, by a first base station central unit (BS-CU) with one or more wireless devices, packets via a first cell operating in an unlicensed spectrum; receiving, by first BS-CU from a first base station distributed unit (BS-DU), a channel occupancy ratio (CR) of the first cell, wherein the CR is for a plurality of time intervals and indicates utilization of unlicensed channel resources that have been utilized for transmissions by the first cell; and transmitting, by the first BS-CU to a second base station, the CR.
 2. The method of claim 1, wherein the first BS-CU communicates with the one or more wireless devices via the first BS-DU
 3. The method of claim 1, wherein the CR is determined by the BS-DU.
 4. The method of claim 1, wherein the BS-CU and the BS-DU are comprised by a first base station.
 5. The method of claim 1, wherein the second base station comprises a second BS-CU.
 6. The method of claim 1, further comprising receiving, by the BS-CU from the BS-DU, at least one of: a RSSI of the first cell; or a channel busy ratio (CBR).
 7. The method of claim 1, further comprising determining a combined resource information of the first cell, the combined resource information comprising the CR, the RSSI, and the CBR.
 8. The method of claim 7, further comprising transmitting the combined resource information of the first cell to the BS-DU.
 9. The method of claim 8, wherein the BS-DU assigns, based on the combined resource information, radio resources for a second wireless device.
 10. The method of claim 1, wherein the BS-CU receives a second CR from the BS-DU.
 11. A base station central unit (BS-CU) comprising: one or more processors; and memory storing instructions that, when executed by the one or more processors, cause the BS-CU to perform operations comprising: communicating, with one or more wireless devices, packets via a first cell operating in an unlicensed spectrum; receiving, from a first base station distributed unit (BS-DU), a channel occupancy ratio (CR) of the first cell, wherein the CR is for a plurality of time intervals and indicates utilization of unlicensed channel resources that have been utilized for transmissions by the first cell; and transmitting, to a second base station, the CR.
 12. The BS-CU of claim 11, wherein the first BS-CU communicates with the one or more wireless devices via the first BS-DU
 13. The BS-CU of claim 11, wherein the CR is determined by the BS-DU.
 14. The BS-CU of claim 11, wherein the BS-CU and the BS-DU are comprised by a first base station.
 15. The BS-CU of claim 11, wherein the second base station comprises a second BS-CU.
 16. The BS-CU of claim 11, wherein the operations further comprise receiving, by the BS-CU from the BS-DU, at least one of: a RSSI of the first cell; or a channel busy ratio (CBR).
 17. The BS-CU of claim 11, wherein the operations further comprise determining a combined resource information of the first cell, the combined resource information comprising the CR, the RSSI, and the CBR.
 18. The BS-CU of claim 17, wherein the operations further comprise transmitting the combined resource information of the first cell to the BS-DU.
 19. The BS-CU of claim 18, wherein the BS-DU assigns, based on the combined resource information, radio resources for a second wireless device.
 20. The BS-CU of claim 11, wherein the BS-CU receives a second CR from the BS-DU. 